HAVANA, Cuba (CNN) - Thousands packed Havana's Revolution Square on Saturday for International Workers' Day, drawing hoards of Cuban demonstrators, spectators, and trade unionists from around the world - including the United States and the United Kingdom.

"I've never seen anything like it," said Brian Hattsberger, a British labor unionist in attendance, wiping the sweat from his brow with his red labor hat. "It's just amazing."

For years since Cuba's bearded revolutionaries toppled then-dictator Fulgencio Batista on New Year's Day over half a century ago, residents have gathered in Havana on May 1 to listen to hours-long speeches from their former president Fidel Castro.

The elder Castro made his last showing in 2006 before stepping down because of illness, at first temporarily and then permanently, leaving the reins to his younger brother Raul.

Since then, neither Castro has made a major speech on May Day. This Saturday was no different.

In a carefully choreographed show of force, thousands took to the streets, carrying placards with the faces of Che Guevara, Fidel and Raul Castro, and waving Cuban flags as they sang and sweated beneath the hot Carribbean sun.

"I am marching for Cuba and for the Cuban revolution," said one Cuban marcher, as she passed through the square.

Cuba had billed this year's march as a rebuke to international criticism from Europe and Washington over human rights issues recently bubbling up in the communist nation.

In February, dissident Orlando Zapata Tamayo, who was jailed in 2003 during the crackdown on political opposition, died after a hunger strike that lasted for more than 80 days. He began the strike to demand better prison conditions.

In an unprecedented government statement, Raul Castro said he "lamented the death of Cuban prisoner Orlando Zapata Tamayo, who died after leading a hunger strike."

He blamed the United States for the death, but did not explain why.

"Tortured people do not exist," Castro added.

Recently, an opposition group who call themselves the "Ladies in White" - the relatives of dissidents jailed in a 2003 crackdown - have met a recurring resistance from large groups of pro-government demonstrators who surround the women and drown out their chants of "Freedom" with such phrases as "This street belongs to Fidel."

The women on occasion are detained briefly by police before being driven back to their homes.

Saturday marks only the second International Workers' Day since U.S. President Barack Obama took office. At the time of his election, Obama elicited a sense among many Cubans that they might finally see an end to the economic trade embargo that has been in place since former President John F. Kennedy was in office.

While Obama eased restrictions on small ticket items such as family travel and telecommunications and sent high-ranking envoys to Havana to foster fresh migration talks, broader discussions now appear at a standstill following a storm of criticism over Zapata's death and increasingly rountine counter-demonstrations in support of the government that overpower the handful of weekly protests.

Saturday's May Day march began around 8 a.m. ET and lasted roughly two hours without incident.