By Mark Felsenthal
WASHINGTON, June 20 (Reuters) - U.S. President Barack Obama has sent an indirect message to Cuban President Raúl Castro through Uruguay's leader, asking Cuba to release a jailed U.S. aid contractor and encouraging political reforms, U.S. officials said on Friday.
It was a rare presidential-level communication between the United States and Cuba, which lack diplomatic relations and have been hostile neighbors for more than 50 years.
Obama and Castro famously shook hands at the funeral for South African leader Nelson Mandela in December, exchanging pleasantries but without discussing matters of state.
Uruguayan President José Mujica, a leftist who has actively sought a role in helping improve U.S.-Cuban relations, visited the White House in May.
At that time, U.S. officials said, Obama asked Mujica to urge Castro to release Alan Gross, who has served four and a half years of a 15-year sentence for attempting to set up an illegal Internet service in Cuba.
The Gross case has impeded any major breakthrough in U.S.-Cuban relations.
"President Obama asked that President Mujica use any opportunity he might have to convey this same message to President Castro," National Security Council spokesman Patrick Ventrell said on Friday.
"With respect to Cuba, President Obama urged President Mujica to use his considerable credibility as a regional leader to encourage political and economic reforms in Cuba, noting that such measures would be well received by the United States and other members of the international community," Ventrell said.
The Uruguayan weekly Busqueda, which first reported on the communication on Thursday, said Mujica delivered a message from Obama to Castro last weekend, when Mujica and Castro attended the Group of 77 summit in Bolivia.
Gross, 65, was arrested in 2009 while trying to establish an online network for Jews in Havana as a subcontractor for the U.S. Agency for International Development (USAID). Cuba considered the program subversive, and in 2011, a Cuban court sentenced him to 15 years in prison.
Cuba has attempted to link his case to those of three Cuban agents serving prison terms in the United States for spying on Cuban exile groups in Florida. The United States has rejected any trade of the Cuban agents for Gross. (Reporting by Mark Felsenthal, writing by Daniel Trotta; editing by Jason Szep and G Crosse)