Ten Yemenis imprisoned without trial in Guantanamo Bay have arrived in Oman where they will be detained for an indeterminate amount of time, the Gulf monarchy's state news agency reported on Thursday, citing an official at its foreign ministry.

The prisoners have been sent to Oman, and not Yemen, for humanitarian reasons as their home country has been embroiled in a brutal civil war since March 2015.

One official familiar with the those being transferred claimed the detainees were “hardcore” terrorists with ties to al-Qaeda and other extremist groups.

However, no specific details were released about the detained men or how long their detention will continue.

OPINION: Obama Never Had a Plan to End What Guantanamo Represents

President Obama came into office in 2009 promising to close the military prison at Guantanamo Bay, founded in 2002 by his predecessor, George W. Bush. However, his plans – not to end indefenition detention without charge, but to transfer the remaining prison population elsewhere, including the U.S. – has met steadfast opposition in Congress.

OPINION: Close Guantanamo and Return It to Cuba 

During his final State of the Union speech on Tuesday, Obama said that closing the prison at Guantanamo Bay would set a positive example for the rest of the world.

"It is expensive, it is unnecessary, and it only serves as a recruitment brochure for our enemies," Obama said. "There's a better way."

The transfer means that the number of detainees moved out of the camp this year to 14.

The administration is looking to transfer more in the coming weeks, which means the number of detainees could fall below 100 for the first time since 2002.

VIDEO: 14th Anniversary of Guantanamo Bay Prison