[Updated at 8:55 a.m.] Deputy Prime Minister Suthep Thuagsuban has been appointed to administer emergency law after anti-government demonstrators broke into the country's parliament.
Thailand's Prime Minister Abhisit Vejjajiva said the measure is effective in Bangkok and nearby provinces and "will limit certain rights of people."
The prime minister stressed that the measure is not mean to disperse people, the decree bans the gathering of more than five persons who are deemed to instigate an emergency situation.
It bans the publishing, broadcasting or spreading information considered a threat to national security and it prohibits people from staying in certain areas. The emergency allows authorities to take actions without court orders, such as summoning people, arresting and detaining people, and embarking on searches.
It allows authorities access to any communications, such as fax or telephone and gives them the power to end communications. Authorities are also permitted to stop Thai citizens from leaving the country.
[Updated at 7:44 a.m.] Thailand's Prime Minister Abhisit Vejjajiva declared a state of emergency Wednesday, not long after anti-government demonstrators broke into the country's parliament.
Speaking on nationwide television, he said the "purpose is to restore peace and order and to stop the spreading of false information to the Thai public."
Vejjajiva said the measure is effective in Bangkok and nearby provinces and "will limit certain rights of people."
Demonstrators Wednesday had been keeping a promise to intensify protests unless Vejjajiva dissolves parliament.
Soon after the prime minister's address, the protesters - known as "red shirts" for their clothing - retreated but surrounded the parliamentary compound, before eventually returning to their gathering point, Phan Fa Bridge.
Lawmakers who were inside the parliament building as the protesters began arriving made a quick exit, some climbing over fences.
A helicopter was dispatched to pick up Deputy Prime Minister Suthep Thuangsuban and some other officials, Abhisit's office said.
The cabinet met to extend the country's Internal Security Act for another two weeks to help maintain order in the capital as the protests show no signs of abating.
The act has been in effect since March 11, two days before the protesters began their mass demonstrations in Bangkok.
On Tuesday, Abhisit spoke on television saying the rallies violated the constitution.
The demonstrators have disregarded all calls to disperse from Bangkok's commercial hub.
The nation's tourism minister, Chumpol Silapaarcha, has said the protests could affect tourism by about 10 percent.
The group, United Front for Democracy Against Dictatorship, is made up of supporters of former Prime Minister Thaksin Shinawatra, who was ousted in a bloodless military coup in 2006.
He fled the country in 2008 while facing trial on corruption charges that he says were politically motivated. He remains hugely popular.
The protesters say Abhisit was not democratically elected and have demanded that he call elections.
[Posted 7:20 a.m.] Thailand's prime minister declared a state of emergency Wednesday amid anti-government protests.