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Fifteen detainees are being transferred from Guantanamo Bay detention facility to the United Arab Emirates, the Defense Department said Monday.

In a statement, the department said that a prison task force unanimously approved the transfer of six of the detainees.

"Periodic review boards" determined that keeping the other nine prisoners was not "necessary to protect against a continuing significant threat," the department said.

Detainees in orange jumpsuits sit in a holding area at Camp X-Ray of Naval Base Guantanamo Bay in this January 11, 2002 file photograph Reuters File

The review boards consist of representatives from "the Departments of Defense, Homeland Security, Justice, and State; the Joint Chiefs of Staff, and the Office of the Director of National Intelligence," the statement said.

Among those to be released were Obaidullah, an Afghan who has said the Taliban forced him to learn about land mines, according to Reuters.

He also alleged that he was tortured and threatened with sexual abuse during his 14 years at the facility, said Naureen Shah of Amnesty International.

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Also on the list wasAbdel Qadir al-Mudafari. Described in Pentagon documents published by Wikileaks as a former bodyguard for Osama bin Laden — a claim which has not been independently verified by NBC News — al-Mudafari was captured among other members of so-called the "Dirty 30," detainees thought to be the best potential sources of information about bin Laden who were subjected to some of the harshest interrogation methods.

The full list is:

Abd al-Muhsin Abd al-Rab Salih al-Busi

Abd al-Rahman Sulayman

Mohammed Nasir Yahi Khussrof Kazaz

Abdul Muhammad Ahmad Nassar al-Muhajari

Muhammad Ahmad Said al-Adahi

Abdel Qadir al-Mudafari

Mahmud Abd Al Aziz al-Mujahid

Saeed Ahmed Mohammed Abdullah Sarem Jarabh

Mohammed Kamin

Zahar Omar Hamis bin Hamdoun

Hamid al-Razak

Majid Mahmud Abdu Ahmed

Ayub Murshid Ali Salih

Obaidullah

Bashir Nasir Ali al-Marwalah

The release, described by Human Rights Watch executive director Kenneth Roth as the single largest transfer from Guantanamo in the facility's 14 year history, comes six months after President Barack Obama announced his long-awaited and much criticized plan to shutter Guantanamo.

“Keeping the facility open is contrary to our values,” Obama explained in February. "It undermines our standing in the world. It is viewed as a stain on our broader record of upholding the highest standards of rule of law."

In a statement, Hina Shamsi, director of the ACLU's National Security Project, described the release Monday as a "welcome advance in the administration’s effort to close Guantanamo."

"As the number of men at Guantanamo dwindles, so does any rationale for keeping the detention camp open," Shamsi said.

"It’s also critically important for the Obama administration to end what Guantanamo represents, which is the policy of indefinite detention without charge or trial."

Republican House Foreign Affairs Committee Chairman Ed Royce has been critical of Obama's push to close the prison, saying that his plan needs to be "fundamentally reassess[ed]."

"Dangerous jihadists are being released to countries with little intention of controlling them," Royce said in a statement last month. “How many more innocent people have to die before the administration wakes up?”

The prison, which once held hundreds of detainees, including Khalid Sheikh Mohammed, has 61 prisoners remaining, the Defense Department said.

Ravil Mingazov, a former ballet dancer and Russian citizen, was the most recent detainee to be approved to leave the prison.

Mingazov was held for 14 years on unproven allegations that he fought for the Taliban. His lawyers asked that he be resettled in England, where his family was granted political asylum.