Gazprom Neft, the oil division of Gazprom, bought a 30 percent stake in four Cuban blocks following a production-sharing agreement signed with Malaysia's Petronas and Cuba's Cubapetroleo, Russia's state-run news agency RIA Novosti reports.
The companies didn't highlight the resource potential off the Cuban coast other than to say Gazprom Neft could help boost production there when drilling starts in 2012.
Environmental groups in Florida in June said they were concerned about the impact of offshore drilling in Cuba's deep waters more than a year after the BP oil disaster off the Louisiana coast.
The National Wildlife Federation said the Cuban wells would be in waters 1,300-4,900 feet deep.
The U.S. Energy Information Agency said most countries in the Caribbean basin are net energy importers, with Cuba ranking 60th in terms of total oil production in 2008.