WASHINGTON - The Pentagon on Thursday announced the transfer of another two inmates from the Guantanamo Bay military prison, bringing the controversial facility's remaining population down to 91.

Tariq Mahmoud Ahmed Al Sawah was sent to Bosnia, while Abd al-Aziz Abduh Abdallah Ali Al-Suwaydi was transferred to Montenegro, the Pentagon said.

According to their leaked prisoner files, Sawah is a citizen of Egypt and Bosnia and Herzegovina, and Al-Suwaydi is from Yemen. The transfers mark another step as the administration of US President Barack Obama struggles to close the facility. About 780 inmates have been held there since it opened in January 2002.

"The United States is grateful to the government of Montenegro for its humanitarian gesture and willingness to support ongoing US efforts to close the Guantanamo Bay detention facility," the Pentagon said in a statement announcing Al-Suwaydi's release.

The statement did not give further details, but typically Guantanamo inmates are released into rehabilitation or reintegration programs.

Al-Suwaydi, 41, was allegedly an Al-Qaeda member and explosives trainer, according to his file. He was captured in Pakistan in February 2002.

Sawah, 58, was captured in December 2001 and first recommended for release in 2007. He allegedly admitted to being in Al-Qaeda and developing explosives for the militant group, including limpet mines for use against US ships and a prototype shoe bomb.

Despite this purported past, Sawah was a "highly prolific source and has provided invaluable intelligence," Sawah's file states. The 2008 document notes he was morbidly obese at the time.

The Pentagon last week announced the transfer of 10 Yemeni inmates to Oman, bringing the prison's population below 100 for the first time since 2002.

"This trickle of transfers should become a torrent. Otherwise, the US risks making this ugly stain on its human rights record permanent," said Naureen Shah, a program director at Amnesty International USA.

Inmates are kept without recourse to the regular US legal processes and some likely will die in prison without ever being convicted of a crime.

Of the remaining 91 inmates, 34 have been approved for transfer. The rest face ongoing, indefinite detention.

"We are looking at ways for that group of people who we believe can probably not be transferred safely to have an enduring place in the United States," Pentagon spokesman Captain Jeff Davis said.

Obama - who says Guantanamo serves as a propaganda tool for militants - wants the inmates to be transferred to federal facilities in the United States, and has asked the Pentagon to come up with proposals for a "Guantanamo North" so he can shut the Cuban prison.

But delays, bureaucratic hurdles and political opposition mean the clock may tick down on his presidency before Guantanamo closes.

Davis said the Pentagon's proposals for "Guantanamo North" are currently with the White House.