WASHINGTON (AFP)---The lawyer for US contractor Alan Gross, jailed in Cuba, rejected claims Thursday by Havana that he is in good health and renewed allegations by the man's relatives that his condition is worsening.

A Cuban foreign ministry official, Josefina Vidal, insisted this week that Gross -- who has spent nearly three years in captivity and is now 63 -- is in good health, prompting a denunciation from the American's lawyer.

"First, Ms. Vidal has never met Alan," attorney Jared Genser said in a statement.

"She is in no position to offer an opinion about his health situationwhen she has never taken the time to enquire about his health from him. I would urge her to go meet Alan directly."

Genser issued his remarks after recent visits by Gross's wife, who said her husband has lost more than 100 pounds (48 kilos), is suffering from chronic arthritis and is depressed.

Gross was arrested in December 2009 and tried for distributing laptops and communications equipment to the country's small Jewish community, under a US State Department contract.

In 2011, he was sentenced to 15 years in prison for "acts against the independence or territorial integrity" of the communist-ruled island.

Cuba has said it is open to a deal for his release and is awaiting a response from Washington.

The Havana government has said it might be willing to swap Gross for five Cuban agents imprisoned in the United States since 1998 and serving long prison sentences for espionage.

Washington, however, has ruled out any such exchange, and Genser said no serious talks on Gross's release are under way.

"My independent conversations with officials at the White House, State Department and on Capitol Hill make clear that the Cuban government has been repeatedly asked through formal and informal channels to explain how Alan Gross's case can be resolved," he said.

"It has been consistently reported to me that Cuban government officials have been unwilling to put a concrete proposal on the table."