The Cuban government said Wednesday that a biopsy established that U.S. contractor Alan Gross, who is serving a 15-year prison sentence here for subversion, does not have any cancerous lesions.

Gross is receiving "adequate treatment" for his various health problems, including any chronic ones and those "typical for his age" that he had before being arrested in Havana, the foreign ministry said in a statement.

"Gross maintains a voluntary regimen of systematic physical exercise and is following a balanced diet of his choosing, which has allowed him to eliminate his earlier condition of obesity," said the statement.

The jailed American is in weekly telephone contact with his wife and family and receives monthly visits by officials at the U.S. Interests Section in Havana, the ministry said.

Gross' Cuban medical team met Monday with U.S. diplomats, including the chief of the interests section, John Caulfield, and provided them with the latest information on the prisoner's health, including the result of a biopsy performed on a lesion in his shoulder at the end of October.

"This test could not be performed earlier, given that Mr. Gross refused it," said the foreign ministry.

Now 63, Gross was arrested in Havana on Dec. 3, 2009, in possession of satellite communications equipment he said he was planning to distribute among Cuba's Jewish community.

Havana says he was illegally aiding dissidents and inciting subversion on the Communist-ruled island. Last August, Cuba's highest court upheld the 15-year jail sentence imposed on Gross five months earlier.

Gross was in Cuba as an employee of a Maryland firm contracted by the U.S. Agency for International Development.

Washington insists that Gross is innocent and demands his "immediate and unconditional" release.

Gross and his wife recently filed a lawsuit against the United States and the company that hired him for not warning him about the risks of traveling to Cuba. EFE