Cuba and Venezuela are set to sign cooperation deals worth about $3 billion later on Saturday, underscoring Caracas' role as the communist-run island's closest political and commercial ally.

Venezuela, an OPEC member, has become a vital source of energy and trade for Cuba in recent years and it exports 98,000 barrels of crude a day to the Caribbean country on favorable financing terms.

We're going to seal a series of new deals that exceed $2 billion, almost $3 billion, Chavez told reporters when he arrived in Havana late Friday.

Venezuelan Energy Minister Rafael Ramirez said earlier on Friday that Chavez would sign 285 accords for $3.19 billion in areas including education, sport, fishing, energy and technology.

Cuba, which is heavily dependent on imports of fuel and food, pays part of its Venezuelan oil bill with the services of 40,000 doctors and other professionals.

Chavez has joined Cuba in promoting leftist revolution as an alternative to U.S. free-market trade proposals and the two nations are at the heart of the ALBA trade alliance, which aims to promote cooperation among leftist regional governments.

Chavez and Raul Castro, who took over the presidency from his ailing brother Fidel last year, will be joined Sunday by other members of the ALBA group, including Bolivian President Evo Morales.

Trade between Cuba and Venezuela reached $5.28 billion last year, compared with $945 million in 2003, according to statistics from the Cuban government.

(Reporting by Nelson Acosta and Helen Popper; Editing by Peter Cooney)