In the latest instance of the unrest in Syria spilling across the border into Lebanon, deadly clashes broke out in Beirut on Monday following the shooting death of two anti-Assad clerics at the hands of soldiers.

Two people were killed and 18 wounded in the Lebanese capital early Monday as clashes flared between rival political parties - one supporting Syrian President Bashar al-Assad and the other opposing him - the country's National News Agency said.

The violence followed the killings just hours earlier of two anti-Assad clerics who were shot at a military checkpoint in northern Lebanon.

The histories of Lebanon and Syria have long been intertwined.

Syrian troops were deployed in Lebanon between 1976 and 2005, primarily in the north. They were initially called in to help stop a brewing civil war, but maintained their significant presence, which once numbered 40,000, long afterward.

In a country struggling to maintain a delicate balance among its religious and ethnic sects, resentment from the occupation lingers.

Some Sunni Muslims are staunchly anti-Assad and sympathize with the Sunni-led uprising in Syria calling for his ouster. Support for Assad is also plentiful, particularly in the south.

A bomb exploded in the volatile Syrian city of Daraa near a convoy carrying U.N. observers and the head of the monitoring team Wednesday, the United Nations said.

There were no casualties among the observers, but several Syrian soldiers were injured and hospitalized, the U.N. Supervision Mission in Syria said.

"This was a graphic example of what the Syrian people are suffering on a daily basis and underlines the imperative for all forms of violence to stop," Maj. Gen. Robert Mood, head of mission and chief military observer, said in a statement.

International envoy Kofi Annan told the U.N. Security Council on Tuesday that the international observer mission to Syria is the last chance to stabilize the country. Otherwise, he said, it could plunge into a full-scale civil war.

Annan made the statement a day after U.N. Secretary-General Ban Ki-moon said the situation has become one of the "most serious and gravest concerns of the international community."

"More than 9,000 people have been killed during the last 14 months. This is totally unacceptable and an intolerable situation," Ban said.

But the killing hasn't stopped.

At least 17 people died across Syria on Tuesday, including a soldier who was shot weeks ago in Aleppo while trying to defect and a young man shot by security forces in Hama, the opposition Local Coordination Committees (LCC) of Syria said.

In addition, the LCC reported explosions in Damascus, Homs and Hama.

Amid the violence and pressure on President Bashar al-Assad to stand down, the Syrian government touted a "wide turnout" for parliamentary elections Monday when more than 7,000 candidates vied for 250 parliamentary seats.

U.N.-Arab League special envoy Kofi Annan has expressed dismay over reports that the Syrian government resumes brutal attacks on cities once U.N. monitors leave - the latest sign that diplomatic efforts are failing to quash the bloodshed in the country.

"I am particularly alarmed by reports that government troops entered Hama (Monday) after observers departed, firing automatic weapons and killing a significant number of people," Kofi Annan told U.N. Security Council members Tuesday. "If confirmed, this is totally unacceptable and reprehensible."

Thirty observers are expected in the country by Monday, and 100 within a month, said U.S. Ambassador to the U.N. Susan Rice, citing comments by Herve Ladsous of U.N.'s Department of Peacekeeping Operations.

"Mr. Ladsous reported that the Syrian government has refused at least one observer based on his nationality, and that Syrian authorities have stated they will not accept (monitoring mission) staff members from any nations that are members of the 'Friends of Democratic Syria,'" Rice said Tuesday. "He underscored that from the U.N. point of view this is entirely unacceptable."

he wives of the British and German ambassadors to the United Nations have taken on Syria's first lady in an online video, calling on Asma al-Assad to "stop your husband" and "stop being a bystander."

The roughly four-minute video, posted to YouTube, juxtaposes pictures of an elegant al-Assad, the wife of Bashar al-Assad, against images of other Syrian women, dead and wounded children.

"We want her (al-Assad) to speak out for the end of violence. That it what we want. Stop the bloodshed. Stop it now. We know this is a risk for you, but take this risk," Huberta von Voss-Wittig, the wife of Germany's U.N. ambassador, told CNN late Tuesday.

A U.N. diplomat said the video was produced by Voss-Wittig and Sheila Lyall Grant, the wife of Britain's U.N. ambassador, "on their own initiative."

The first members of a U.N. observer team will begin their work in Syria on Monday, tasked with monitoring a tenuous cease-fire that is showing signs of collapse.

"They will be liaising with the Syrian government, security forces and the opposition members to establish the monitoring process across the country," said Kieran Dwyer, a spokesman for peacekeeping missions at the United Nations.

But since the deadline for the cease-fire passed on Thursday morning, reports of deadly violence at the hands of the regime continued.

At least 23 people died across Syria on Sunday, including 11 in the besieged city of Homs, opposition activists said. Government helicopters pummeled Homs from the sky, said the Local Coordination Committees of Syria, a network of opposition activists.

But the state-run Syrian Arab News Agency blamed "armed terrorists" for violating the cease-fire, quoting an unnamed military official's assessment that the groups "have hysterically escalated their aggressions on the army, the law enforcement forces and the civilians."

Government helicopters pounded the besieged city of Homs from the sky, opposition activists said Sunday, three days after a so-called cease-fire in Syria.

In addition, "one bomb is being shelled every 10 minutes from the military academy, aiming at al-Wair neighborhood in Homs," said the Local Coordination Committees of Syria, a network of opposition activists.

At least nine people died across Syria on Sunday, including six in Homs, said the opposition Syrian Network for Human Rights. Two died in Aleppo a day after they were injured when regime forces opened fire at a funeral procession, the group said.

The latest reports of violence came three days after a deadline to stop the bloodshed and one day after the U.N. Security Council voted unanimously  to authorize unarmed observers to travel to Syria to monitor the shaky cease-fire.

Syrian forces pounded cities across the nation, opposition activists said, as a United Nations-brokered deadline for a troop withdrawal came and went Tuesday

At least 40 people, including three children, were killed Tuesday; 25 were in the besieged city of Homs, the opposition Local Coordination Committees of Syria said. Tuesday's toll continues a shocking surge in violence and atrocities ahead of the deadline for troops to withdraw.

The Syrian government, however, said it had taken steps to abide by the peace plan laid out by U.N.-Arab League special envoy Kofi Annan.

"We did withdraw some military units from some provinces, in accordance with point C of Annan's plan," Foreign Minister Walid Moallem said after meeting with Russia's foreign minister in Moscow.

President Bashar al-Assad's regime had agreed to the deadline, but demanded that its opponents, whom it calls armed terrorists, put down their weapons. Damascus also wanted a promise from foreign governments not to fund opposition groups.

Russian Foreign Minister Sergey Lavrov said the Syrian government could have been more active in implementing the peace plan, but he urged heightened international pressure on opposition groups.

"But on the other hand," he said, "we cannot overlook the fact that Kofi Annan's proposals have not been agreed to by some of the opposition groups including the well-known Syrian National Council."

Sheikh Anas Airout, a senior member of the council, told CNN that Annan did not get an agreement from the opposition body but that the Free Syrian Army, the main armed opposition group made up mainly of defected soldiers, provided an explicit commitment to abide by the cease-fire as long as the regime stopped its attacks.

With both the regime and rebel fighters refusing to back down until the other side does, prospects paled for an end to the fighting. And the bloodshed continued unabated.

A deadline for Syrian troops to withdraw from cities came and went Tuesday morning, but opposition activists say regime's onslaught rages on.

One activist in the besieged city of Homs said fresh shelling rained on two neighborhoods late Tuesday morning.

"Tanks hitting those areas remain in al-Qusoor neighborhood. So there is not a tank that pulled out from there," said the opposition activist, identified only as Omar for safety reasons.

Hours before the deadline, reports of mounting carnage left some world leaders doubtful of the regime's promises.

"Should the Syrian government yet again refuse to implement its commitments, make promises and then break them and continue and escalate the killing, then I think it will be clear to all that there isn't yet prospect for diplomatic solution," Susan Rice, U.S. ambassador to the United Nations, said Monday. "We still hope that that's possible, we still want to give that a final chance, but I don't think we, or anybody else, are particularly optimistic."

Syrian security forces have summarily executed at least 101 people, including civilians, since late 2011 in attacks on cities and towns, Human Rights Watch said in a report released Monday.

The report "documents the involvement of Syrian forces and pro-government shabeeha militias in summary and extrajudicial executions of defecting soldiers, opposition fighters and opposition supporters, as well as civilians who appeared to have had no part in the confrontation with the authorities other than being residents of opposition strongholds," according to the human rights organization.

The 25-page report, "In Cold Blood: Summary Executions by Syrian Security Forces and Pro-Goverment Militias," was based on more than 30 interviews with witnesses to the executions, Human Rights Watch said.

While it was not possible to verify the exact numbers of victims of such executions, the organization said it had documented 12 cases in Idlib and Homs governorates involving at least 101 victims since December 2011. Human Rights Watch said it had received reports of other incidents, but only included in its report incidents where eyewitnesses were interviewed.

Top U.N. officials and the Security Council leaned on the Syrian regime Thursday, urging it to fully carry out a peace plan it promised to heed.

Syria said Thursday that it had taken several steps to comply with a peace plan championed by U.N. envoy Kofi Annan, including the withdrawal of troops from three regions and the expansion of Red Cross humanitarian access.

But more needs to be done, U.N. officials say, with imposing a cease-fire at the top of the agenda.

The president of the International Committee of the Red Cross, Jakob Kellenberger, arrives Monday in Syria for two days of talks with senior Syrian officials that are intended to respond to the humanitarian needs of those Syrians wounded and/or displaced. He arrives amid ongoing violence which killed at least 47 on Monday alone, according to opposition groups, and continuing international outcry against the government of Syrian President Bashar al-Assad.

"I am determined to see the ICRC and the Syrian Arab Red Crescent expand their presence, range and scope of activities to address the needs of vulnerable people," Kellenberger said in a news release about his third such visit since last June. "This will be a key element of my talks with the Syrian officials."

Kellenberger, who was to meet with Minister of Foreign Affairs Walid al-Mu'alem, Minister of the Interior Major-General Mohamad al-Shaar, and Minister of Health Dr Wael al-Halki, will also raise the issue of access to all places of detention. "Visiting people who have been detained remains a priority for us," he said. "I will also further discuss practical measures for implementing our initiative for a daily two-hour cessation of fighting. A daily pause in the hostilities is essential in order to evacuate wounded people and deliver aid if and when the fighting intensifies."

The release said the ICRC has, in recent weeks, obtained greater access to some of the areas affected by the unrest.

The Syrian military clashed with defectors in the capital of Damascus on Saturday as regime forces bombarded other towns with heavy gunfire despite the United Nations' call for a cease-fire, opposition activists said.

Gunfire between both sides erupted in the Homs neighborhoods of Baba Amr and Jouret Al-Arayes, the opposition Local Coordination Committees of Syria said. Early-morning shelling also targeted other various areas in Daraa, Idlib, Hama and the Damascus countryside, opposition activists said.

The latest violence comes after a U.N. special envoy ordered President Bashar al-Assad to implement a peace plan and not await concessions from the opposition.

"The government must stop first and then discuss a cessation of hostilities with the other side and with the mediator," Ahmad Fawzi, a spokesman for special envoy Kofi Annan said Friday. "We expect him to implement this plan immediately."

A day after news broke that Syrian President Bashar al-Assad accepted a plan to forge peace, fresh clashes broke out once again across Syria on Wednesday, opposition activists said.

Three members of the Syrian security forces were killed and four defecting soldiers were injured from intense clashes at an entrance to the western city of Rastan, which security forces have been trying to storm, said the Syrian Observatory for Human Rights, an opposition group.

And fierce fighting erupted between the Syrian security forces and a group of defectors in the southern Daraa province, the observatory said. The group said clashes began after an army soldier threatened residents in the town of Busr el-Harir to hand over the group of defectors or face a military operation.

Opposition activists have said Busr el-Harir has endured shortages of food and medicine since the Syrian army surrounded the town weeks ago.

The reports of violence come after al-Assad accepted a plan laid out by U.N.-Arab League special envoy Kofi Annan to help end the bloodshed.

The Syrian government has accepted U.N. envoy Kofi Annan's plan to forge peace and end violence, Annan's spokesman said on Tuesday.

Annan has offered Syria a six-point plan - supported by the U.N. Security Council - as a way to halt the violence.

The proposal seeks to stop the violence and the killing, give access to humanitarian agencies, release detainees, and start an inclusive political dialogue to address the legitimate aspirations and concerns of the Syrian people, according to a U.N. statement.

U.N.-Arab League special envoy Kofi Annan arrived in Beijing on Tuesday to rally support in helping end the bloodshed in Syria.

Annan's visit to China comes after a stop in Russia, the other country that has stymied U.N. Security Council attempts to condemn the Syrian regime.

During his two-day trip to China, Annan will meet with foreign ministry officials, China's state-run Xinhua news agency said.

Both China and Russia have said they want the violence to stop but argued that draft resolutions by Security Council peers were not evenhanded. Both countries have major trade ties with Syria, but have said they are not trying to protect a regime.

Disjointed factions of the Syrian opposition are meeting Monday in Istanbul in an effort to form a unified voice ahead of the next week's "Friends of Syria" conference.

Turkey and Qatar urged opposition groups to attend the conference, which they said "will bring all major opposition groups and figures committed to a peaceful political transition in Syria," according to an invitation sent to prospective attendees.

The meeting comes as the reported death toll from a government crackdown mounts inside Syria. At least 14 people were killed across Syria on Monday, the opposition Syrian Network for Human Rights said.

The goal of Monday's conference is "for all forces and parties of the opposition not to be a union, but at least to have a united purpose," said Amar Qurabi, leader of the National Change Current opposition group.

Disjointed factions of the Syrian opposition are meeting Monday in Istanbul in an effort to form a unified voice ahead of the next week's "Friends of Syria" conference.

Observers of the Syrian crisis have bemoaned a lack of unity among the various Syrian opposition groups as they struggle to topple President Bashar al-Assad's rule.

The goal of Monday's conference is "for all forces and parties of the opposition not to be a union, but at least to have a united purpose," said Amar Qurabi, leader of the National Change Current opposition group.

At least nine people were killed across Syria on Monday, the opposition Syrian Network for Human Rights said. The dead include four men gunned down in Homs when residents tried to retrieve two bodies, the group said.

The United States and Turkey are in "full agreement" on the next steps on Syria as world leaders continue trying to stop the year-long massacre that has killed thousands.

U.S. President Barack Obama met with Turkish Prime Minister Recep Tayyip Erdogan on Sunday in South Korea, ahead of this week's nuclear summit in Seoul.

The meeting was aimed at "syncing up" with Turkey - a former Syrian ally - before Istanbul hosts the next "Friends of Syria" meeting on April 1, a senior Obama administration official said. A goal of that conference is to exert pressure on Syrian President Bashar al-Assad's regime for its brutal crackdown on civilians.

Obama and Erdogan expect the upcoming conference to enhance ways to provide "non-lethal" aid to the opponents of the Syrian regime, such as medical supplies and communications equipment, said Ben Rhodes, a U.S. deputy national security advisor.

"We cannot be spectators," Erdogan said Sunday.