Russia announced Saturday it is negotiating major investments in Cuba's oil and nickel industries, just days ahead of an official visit by Russian President Dmitry Medvedev.

Russian ambassador Mikhail Kamynin told the weekly Opciones there were deals under consideration with specific Russian firms to search for oil offshore in Cuba's exclusive economic zone in the Gulf of Mexico.

Companies from Spain, Norway, India, Canada, Vietnam, Malaysia, Venezuela and Brazil already are working on the search that Cuba hopes will turn it from a cash-strapped developing country into an oil exporter with funds to propel its communist regime well into the future.

Cuban authorities in October announced that the Caribbean nation's crude reserves were more than double what had been thought -- 21 billion barrels of crude.

Kamynin said Russian firms were expected to be involved in building crude oil and oil derivative storage tanks and in modernizing pipelines.

The Russian ambassador also said there were plans for a bilateral deal between Russia's NorNickel and Cubaniquel to build a plant in Holguin province.

He also said there was interest in making Havana an air transport hub for tourists arriving from Europe on Aeroflot flights.

The Russian president is due in Havana Thurday on a Latin American tour that includes stops in Peru, Brazil and Venezuela.

Last week Chinese President Hu Jintao visited the Americas' only communist country and proposed joint investments with Havana worth 1.5 billion dollars in oil, mining, renewable energy and tourism, Opciones reported.

Cuban President Raul Castro, 77, took over from his ailing brother Fidel Castro, 82, officially in February. The elder Castro was at Cuba's helm for five decades.