Havana: Cuba prepared a huge military parade on Saturday to celebrate the 50th anniversary of its victory over the CIA-backed Bay of Pigs invasion for a Communist Party congress setting new political and economic goals.

Painters, electricians and audio operators put the finishing touches on Plaza de la Revolucion, as troops drove tanks and other military vehicles to their designated locations along the streets.

Children, youth and veterans will precede the parade of troops and weaponry, local television reported.

As a symbol of the revolution's future, thousands of youths will bring up the rear of the parade, after which the Cuban Communist Party will begin its first party meet in 14 years.

Tens of thousands of Havana residents have been invited to participate in the parade by their student organisations, trade unions and the Committees for the Defense of the Revolution community groups that promote social welfare.

A little ways away from the square, masons and painters were working overtime to renovate the street corner where leader Fidel Castro proclaimed the socialist character of the revolution, a day before 1,400 US-backed Cuban exiles landed at the Bay of Pigs.

Within just 72 hours of bloody combat on Playa Larga and Playa Giron 200 kilometers southeast of Havana, Castro had routed out the invaders in what Cuba celebrates as "the first great defeat of imperialism in Latin America."

During the Communist Party congress, thousand delegates are to vote on economic reforms proposed by President Raul Castro, update the country's one party political system, and either re-elect or relieve an ailing 84-year-old Fidel as party leader.

Warning "either we change course or we sink," the 79-year-old Raul convened the congress to recast Cuba's Soviet-style centralised system "without restoring capitalism," or deviating from the socialist path his brother blazed a half century ago.