WASHINGTON 

American citizen Alan Gross, held at a Cuban prison for five years, was released Wednesday, raising high hopes of a thaw in relations between the U.S. and Cuba, U.S. officials said.

"This morning, Alan Gross, 65, has departed Cuba on a U.S. government plane bound for the United States. Mr. Gross was released on humanitarian grounds by the Cuban government at the request of the United States," senior U.S. administration officials said.

President Barack Obama is expected to speak about Gross's release later Wednesday, which is seen as a huge development in U.S.-Cuba relations that have been strained by a decades-long embargo. Cuban President Raul Castro is also expected to make a statement.

Gross's release followed secret negotiations in Canada and the Vatican that resulted in a spy swap between the U.S. and Cuba. The secret talks were held since June 2013. 

The swap included the release of three Cuban intelligence assets being held in the U.S., for the release of an unidentified American intelligence asset held in Cuba. 

Five Cubans were convicted in 2001, but two of them were released after completing their sentences. Cuba arrested Gross on Dec. 3, 2009, and convicted the U.S. Agency for International Development subcontractor to 15 years in prison for allegedly importing banned technology and trying to establish clandestine internet service for Cuban Jews.

The Cuban regime accuses the American aid agency of playing a negative role in the 1959 revolution that brought Fidel Castro to power.

According to Gross's lawyer and his family, the American was "mentally vanquished, gaunt, hobbling and missing five teeth."

Also, it was reported in December 2014 that Gross refused to be treated by doctors in Cuba and had threatened to go on hunger strikes if he was not released unconditionally.

In a statement marking the fifth anniversary of Gross’ detention earlier this month, Obama had hinted his release could lead to a thaw in relations with Cuba.

“The Cuban government’s release of Alan on humanitarian grounds would remove an impediment to more constructive relations between the United States and Cuba,” Obama was quoted as saying in the statement.

www.aa.com.tr/en