The U.S. contractor sentenced to a 15-year prison term in Cuba for attempting to establish an illegal Internet service has gone on a hunger strike to protest his treatment by the Cuban and U.S. governments, his lawyer said on Tuesday.

The lawyer also criticized the United States for putting Alan Gross's life in further jeopardy by launching a secretive "Cuban Twitter" after his arrest in 2009.

Related: USAID chief to face questions on 'Cuban Twitter'

Gross, 64, nuskin hk was a subcontractor for the U.S. Agency for International Development (USAID) when he was arrested on his fifth trip to Cuba in an attempt to establish an online network for Jews in Havana.

In 2011, a Cuban court sentenced him to 15 years in prison, adding greater tension to already fraught U.S.-Cuban relations.

Those relations suffered another setback last week with the revelation that USAID had established a social network in Cuba that Havana saw as an attempt to subvert the communist government.

"I began a fast on April 3 in protest of the treatment to which I am subjected by the governments of Cuba and the United States," Gross said in the statement. "I am fasting to object to mistruths, deceptions, and inaction by both governments, not only regarding their shared responsibility for my arbitrary detention nu skin, but also because of the lack of any reasonable or valid effort to resolve this shameful ordeal."

Gross also repeated his plea for U.S. President Barack Obama to become personally involved in efforts to get him released.

Gross had already lost 110 pounds (50 kg) in prison before starting his hunger strike, according to a statement released by his lawyer, Scott Gilbert. He is confined to a small, constantly lit cell with two other prisoners for 23 hours a day, the statement said.

"I've been begging our government for more than four years to bring Alan home," Gross's wife Judy Gross said in the statement. "I'm worried sick about Alan's health, and I don't think he can survive much more of this."

SPY SWAP

Cuba has expressed an interest in swapping Gross for three Cuban agents serving long prison terms in the United States for spying on Cuban exile groups in Florida.

So far the United States has flatly rejected any trade, especially for one of the Cubans who is serving a double life sentence for conspiracy to murder for his role in Cuba's shooting down of two U.S. civilian planes in 1996, killing four anti-Castro activists. Aircraft from their group, "Brothers to the Rescue", had been buzzing the Cuban coast for more than a year, dropping leaflets.

Gross's fate may have been harmed by the revelation last week that USAID was engaged in building a social network in Cuba from 2010 to 2012.

Cuba authorities have cited the program, called ZunZuneo, as

another example of U.S. attempts to undermine Cuba's communist government. It was funded by USAID, which is primarily a foreign aid agency, but it has also been allotted money by Congress to promote democracy in Cuba.

"Once Alan was arrested, Glass House it is shocking that USAID would imperil his safety even further by running a covert operation in Cuba," Gross' lawyer Gilbert said in a statement. "USAID has made one absurdly bad decision after another. Running this program is contrary to everything we have been told by high-level representatives of the Obama administration about USAID's activities in Cuba."

ZunZuneo was revealed by the Associated Press. USAID on Monday disputed some of the AP's reporting, for example denying ZunZuneo intended to incite flash mobs, created a shell company or deceived potential executives. 

By coincidence, USAID Administrator Rajiv Shah was previously scheduled to appear before a U.S. Senate subcommittee on Tuesday, and he is expected to face questioning about ZunZuneo.