Two Guantanamo Bay inmates sent to Bosnia and Montenegro
The US flag at the US Naval Base in Guantanamo Bay, Cuba, August 7, 2013 (AFP Photo/Chantal Valery)

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.

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 United States coordinated with the government of Montenegro to ensure this transfer took place consistent with appropriate security and humane treatment measures."

The statement did not give further details, but typically Guantanamo inmates are released on condition they undergo a rehabilitation or reintegration program to make sure they do not threaten US security interests.

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 jihadist group, including limpet mines for use against US ships and a prototype shoe bomb.

Despite this purported past, he 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.

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

Obama wants these men 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 it is increasingly likely the clock will tick down on his presidency before Guantanamo closes.

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.