Havana, Cuba (CNN) -- Cuba's government Friday disputed claims made by the attorney for imprisoned State Department contractor Alan Gross that his client's health is declining rapidly in a Cuban jail.
"Mr. Alan Gross' health is normal," a statement from Cuba's Ministry of Foreign Affairs said. "He has chronic conditions typical of someone his age, and is being properly treated for them."
Gross, 63, is serving a 15-year prison sentence after being convicted of bringing banned communications equipment to the island.
He was arrested in 2009 after traveling to Cuba while working as a subcontractor on a U.S. Agency for International Development project aimed at spreading democracy.
Gross had argued that he was not trying to overthrow Cuba's government but was working to connect Cuba's small Jewish community to the Internet, a scarce commodity on the island. But Cuban authorities say Gross imported sensitive communications equipment to connect dissidents.
On Thursday, Gross' attorney Peter Kahn said that Gross is suffering from increasingly poor health and that the Cuban government is withholding his medical records from U.S. officials and his family.
"Alan has not only lost more than 105 pounds," Kahn said in a statement. "More recently, a large mass has appeared on the back of his right shoulder."
Kahn said Gross was also having trouble walking.
In the statement released Friday, the Cuban government denied withholding Gross' records and called the reports of his ill health "distortions."
"Cuba demands that this campaign of fabrications ceases," the statement said. "Should it continue, there will be no other alternative than to publish abundant information on the subject."
The statement said Cuban authorities had so far declined to comment in detail about Gross' health out of respect for "his right to the privacy of doctor-patient information."
Kahn expressed thanks for the release of the records, but said, "It is unfortunate that it took more than a month for them to do so, despite repeated requests."
"We will reserve any further comment until after Alan's U.S. doctors have an opportunity to review and analyze the medical documentation the Cubans are providing," Kahn said. "Suffice it to say, however, anyone who has seen the recent stark photos of Alan understands the family's legitimate concern for his physical and mental well-being."
In May, Gross spoke from the military hospital where he is being held to CNN's Wolf Blitzer in the one weekly phone call he is allowed by Cuban authorities. Gross said he was trying to keep busy by exercising but called his confinement grim.
"The food initially wasn't very good, which is probably why I started losing weight rapidly at first," he said. "The food was infested with insects. There really wasn't much variety or quantity, mostly carbohydrates."
In recent weeks, Cuban officials have suggested a possible exchange of Gross for five Cuban intelligence agents serving prison terms in the United States.
U.S. officials have rejected the possibility of prisoner swap and called for Gross' immediate release.