Oct. 17 (Bloomberg) -- Cuba may have 20 billion barrels of oil in offshore fields, more than double previous estimates, the FolhaNews Internet news service reported, citing Union CubaPetroleo, the country's state oil company.

The estimates are based on comparisons of the geology of fields in U.S. and Mexican waters and if confirmed would make Cuba an oil exporter, FolhaNews, the online news service of the Folha de S. Paulo daily newspaper, said, citing Rafael Tenreyro Perez, CubaPetroleo's head of exploration and production.

The U.S. Geological Survey recently estimated Cuban reserves to be about 9 billion barrels of oil and 180 billion cubic meters of natural gas, FolhaNews reported.

To contact the reporter on this story: Jeb Blount in Rio de Janeiro at jblount@bloomberg.net

Last Updated: October 17, 2008 11:47 EDT