"You should be ready to take up arms at any moment and give your lives if necessary for our nation's independence and the socialist revolution," Chavez said, unsheathing the sword of Venezuelan independence hero Simon Bolivar.

The show of force by the government-organized militia -- whose number is thought to be several hundred thousand nationwide -- appeared aimed at defending his 11-year government from what Chavez and his supporters perceive as the threat of another coup attempt or an attack from abroad.

A fierce critic of what he calls U.S. imperialism, Chavez accuses Washington of backing efforts by Venezuela's upper classes to oust him and arming neighboring Colombia for an invasion of his oil-exporting nation.

Tension between the two countries has risen since Colombia announced that the U.S. military will have access to its bases, and Venezuela ramped up purchases of weaponry from Russia.

U.S. Defense Secretary Robert Gates, who will visit Colombia this week, said on Tuesday he did not see Venezuela as a military threat, adding that it had serious economic problems.

Electricity shortages caused by a severe drought and prolonged economic recession have dented Chavez's popularity ahead of elections for the National Assembly, a prelude to a crucial 2012 presidential vote.

Chavez, a former paratrooper turned socialist revolutionary, said the drop in water levels at the country's largest hydroelectric dam, the Guri, had slowed following recent rain and vowed that the electricity crisis would end this year.

"We cannot allow the bourgeoise to occupy seats in the National Assembly," Chavez, dressed in green military fatigues and a red beret, told his supporters. "We cannot allow them to undo the revolutionary laws."

Three years after he was elected president, his opponents organized massive demonstrations triggering a coup that briefly ousted Chavez on April 11, 2002. The military restored him two days later after his supporters took to the streets.

In a move that will anger its opponents and further polarize Venezuela, Chavez's government decreed April 13 a holiday to be known as the "Day of National Jubilation."