"The imperialist, genocidal, fascist attitude of the U.S. president has no limits. I think Hitler would be like a suckling baby next to George W. Bush," Chavez said from a stage decorated with a huge red image of himself as a young soldier.

Already frayed ties between the United States and the socialist leader worsened further this week after Chavez expelled a U.S. military attache accused of espionage and the White House responded by ordering out a Venezuelan diplomat.

Chavez, a retired army paratrooper who often accuses Washington of trying to overthrow him, warned he could shut Venezuelan oil refineries in the United States and sell oil for the U.S. market elsewhere if Washington cuts off ties.

U.S. officials have made no suggestion they plan to break relations. Washington has repeatedly dismissed Chavez's threats and charges as inflammatory rhetoric aimed at stirring up nationalist sentiment among his poor supporters.

Washington and Caracas recently locked horns over a U.S. block on sales of Spanish military equipment to Venezuela. The Spanish aircraft contained U.S.-made technology, which requires countries to get Washington's clearance for the sale.

Chavez, who last year bought helicopters and 100,000 rifles from Russia, said he would seek to buy more arms to defend Venezuela against any attempt to topple his government. U.S. officials say the purchases could destabilize the region as Chavez moves to create a huge military reservist movement.

"I ask for permission ... to buy another cargo of arms because the gringos want us unarmed. We have to defend our fatherland," he said. "Venezuela needs 1 million well-equipped men and women, and well-armed."

The Venezuelan leader has put himself at the center of regional opposition to Bush, who he calls "Mr. Danger," while Washington brands Chavez a worrying threat to regional stability and criticizes his alliance with Cuba.

Flush with cash from high crude prices, Chavez is promoting socialist reforms at home and aggressively challenging U.S. free-market proposals by allying himself with his South American neighbors, as well as Cuba and Iran.

U.S. officials reject charges the expelled naval attache contacted Venezuelan officers for state secrets. Chavez on Saturday read out e-mails he said were communications between the officers and the U.S. Embassy.

Since his 1998 election, Chavez has clashed repeatedly with the United States, which he accuses of planning an invasion and backing a brief 2002 coup attempt that he survived with the help of loyal troops.

(Additional reporting by Brian Ellsworth)