By JOHN RICE, ASSOCIATED PRESS

HAVANA (AP) - President Fidel Castro said Saturday that the country would defend itself "to the last drop of blood," declaring Cuba unafraid of a U.S. measures to change the island's four-decade-old socialist system.

Speaking for nearly two hours before hundreds of thousands of people during the island's annual May Day celebration, Castro warned U.S. officials to be "calmer, more sensible, wiser and more intelligent" before the expected release of a report by the U.S. government's Commission for a Free Cuba.

The report is to recommend measures to hasten a democratic transition in Cuba and to provide assistance afterward. Cuban officials have speculated that the recommendations could include military action.

Alluding to the upcoming report, Castro said plans were under way to "affect the economy and destabilize the country" and talked about "the same old murderous ideas" - an apparent reference at earlier attempts to assassinate him.

Castro also defended a crackdown on Cuban dissidents recently criticized by the U.N. Human Rights Commission in Geneva. He referred to the dissidents as "mercenaries" in U.S. efforts to topple his government.

He said the United States should "not shout or complain if Cuba adopts the pertinent measures to punish the mercenaries. ... They should know that we have been generous."

He said Cuba "will be defended with laws and will be defended with arms when necessary - until the last drop of blood."

Earlier during the event, Cuba's top labor leader said the island's workers would resist efforts - even a military attack - to change the island's system.

"We don't know what they could invent after these 45 years, in which they after tried just about everything," said Pedro Ross Leal, head of the Cuban Workers Confederation.

The government estimated that 1 million people, most of them wearing bright red T-shirts, jammed into Havana's broad Plaza of the Revolution and adjacent streets for the morning celebration. Many people waved small red-white-and-blue Cuban flags.

Ross told the crowd that workers were ready "to resist and defeat even a pre-emptive war against Cuba, such as one the United States has perpetuated in Iraq for more than a year."

Since the United States launched its war on Iraq, Cuban officials have repeatedly expressed concerns that the island could be next. American authorities deny they are planning military action against Cuba.

In his speech, Castro also defended Cuba's human rights record, saying that the disappearances, torture and extrajudicial killings that plague other nations do not exist here.

Castro bitterly denounced the recent U.N. Human Rights Commission vote, accusing the United States of forcing other nations to support the resolution.

He said the prison camp for terror suspects at the Guantanamo U.S. Naval Base in the island's east is "one of the most grotesque cases of human rights violations." International rights groups have criticized the treatment of more than 600 suspected al-Qaida and Taliban supporters at the camp.

The U.N. resolution last month, adopted 22-21 with 10 abstentions, said Cuba "should refrain from adopting measures which could jeopardize the fundamental rights, the freedom of expression and the right to due process of its citizens."

It also said it "deplores the events which occurred last year in Cuba," a reference to the sentencing of 75 dissidents to prison terms ranging from six to 28 years on charges of working with U.S. diplomats to undermine Cuba's socialist system.