The wife of U.S. contractor Alan Gross expressed concerns about his health after visiting him in a Cuban prison.

"I am devastated by his appearance," Judy Gross said in a statement released Tuesday.

She said her husband has lost 47.7 kilos (105 pounds) and has developed degenerative arthritis and a mass behind his right shoulder blade.

"While his spirit remains strong, I fear he is not going to survive this terrible ordeal," Mrs. Gross said, pleading with Cuban President Raul Castro to "put an end to our anguish and let Alan come home."

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.

The U.S. government has always maintained that Gross is innocent, has criticized the sentence imposed upon him as unjust and has demanded his "immediate and unconditional" release by the Cuban regime.

Washington has dismissed suggestions that it trade five Cuban intelligence agents convicted of espionage in Florida more than a decade ago for the contractor.

Havana, which has publicly hinted it would be prepared to free Gross outright in exchange for the return of the "Cuban Five," acknowledges the men were intelligence agents but says they were spying on Miami's Cuban exile community, not the U.S. government.

The U.S. State Department has repeatedly asked Cuba to heed Gross's request to visit his dying mother as a reciprocal measure after Washington allowed one of the Cuban Five - Rene Gonzalez, on probation in Florida after serving 13 years for espionage - to travel to the island in late March for a brief visit with his terminally ill brother. EFE