In a 4 1/2-hour speech to economists, Castro also took shots at President Bush, saying he "couldn't debate a Cuban 9th-grader." He recited for a half-hour from a published compilation of Bush malapropisms, bent over with laughter as the audience roared.
Castro also challenged Mr. Bush to be clear about how the United States plans to realize a transition to democracy in Cuba. He wondered aloud - again - if it involved a plan to kill him.
"The great difference" between Cuba and the United States is that Cuba "has learned to do a lot with very little," Castro said at the conclusion of the Sixth International Meeting of Economists on Globalization and Development Problems.
Castro noted that many of the more than 1,000 economists in attendance from 50 countries - including some from the United States - had sharply criticized globalization and the "neoliberal" economic policies of industrialized nations.
He lauded U.S. Nobel Prize-winning economist Daniel L. McFadden's "keen observations" - among them that the United States, with a fiscal deficit of more than $520 billion, is managing its economy like a "banana republic."
"This economy is hanging by a thread," Castro said.
Castro also lashed out at the "foolishness" of the U.S. economic blockade that has been in place since the presidency of John F. Kennedy, saying it hadn't stopped Cuba from surpassing the United States in many areas.
The communist-run island has no illiteracy, a lower infant mortality rate than the United States, lower student-teacher ratios and higher levels of educational achievement, he said.
"Bush couldn't debate a Cuban 9th-grader," Castro remarked as he leaned across the podium toward applauding listeners.
Castro's commentary addressed everything from free trade agreements and fluctuating currencies to the current presidential campaign in the United States. At one point - after offering his audience coffee to avoid falling asleep - Castro went on to quote various reports from the U.S. media severely criticizing Mr. Bush, the economy, U.S. unemployment and the war on Iraq.
"What do I know? They're the ones saying this stuff," he said, frequently chuckling and shrugging his shoulders as if he couldn't believe what he was reading.
He talked at length about the Bush administration's Commission for a Free Cuba - a panel set up in October and led by U.S. Secretary of State Colin Powell to plan a strategy for Cuba once the 77-year-old Castro is no longer in power.
When the United States announced creation of the commission, Powell suggested that the goal was not to force Castro out.
U.S. officials talk about a transition, "but how would they make this transition?" Castro asked Saturday, suggesting that "the only way is to proceed with an illegal assassination using the scores of techniques they have available."
Castro challenged Mr. Bush "to have the courage to say whether he is using this power."
Even if his days are numbered by the United States, "don't feel any pity," Castro told his listeners.
"There is no fear. To demonstrate fear would be a mistake. ... and in any case I would have to say to this illustrious gentleman (Mr. Bush) what the Roman gladiators said: 'Hail, Caesar. Those who are about to die salute you."