Fifteen Guantanamo Bay prisoners have been transferred to the United Arab Emirates, leaving 61 detainees at the notorious US military-run jail.

The Pentagon said on Monday that 12 Yemenis and three Afghans, some of whom had been held for more than 14 years without charge, would settle in the UAE in the largest single transfer of Guantanamo detainees during President Barack Obama's administration.

FULL LIST OF DETAINEE TRANSFERS: 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 United States is grateful to the government of the United Arab Emirates for its humanitarian gesture and willingness to support ongoing US efforts to close Guantanamo," the Pentagon said in a statement.

Congress was notified of the transfers as required under US law, the Pentagon added.

Since the September 11, 2001 attacks in New York, about 780 inmates have been kept at Guantanamo.

Amnesty International USA, a rights group, welcomed the announcement as a sign that US President Barack Obama was serious about closing the controversial jail before he leaves office.

Sultan Sooud al-Qassemi, a UAE-based political commentator, called the men "low-value detainees" and said the move was a "humanitarian gesture".

"It's a gesture of goodwill, not only to the US President but also to the Pentagon and the US government in general. Regardless of who becomes the next president, whether it's Hillary Clinton or Donald Trump, the UAE is signalling a continuity in relations between the US and the United Arab Emirates."

Qassemi also said that there might be a "reintegration programme" that the detainees would undergo.

"These individuals have not been charged with any crime. They have been cleared for release, some of them for a number of years. They are low-value detainees," he added.

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Clive Stafford Smith, the director of the British-based advocacy group Reprieve, told Al Jazeera that after years of torture - the UAE, an Arab-speaking country, was a good place for the detainees to "habilitate".

"After being tortured for 14 or 15 years, you can't 'kick them out' and expect them to get on with life.

"One of my clients, Mohsen Aboassy, was 23 when he was sold to the US for a bounty. He's now 37. He wants to get married, he wants a job, he wants to get on with his life. He hasn't met 13 of his nieces and nephews - so there's a lot for him to get back into."

Smith also said that Obama could easily shut down the prison.

"President Obama is the most powerful person on the planet. There are only 61 people left there, 21 have been cleared so that will leave at most 40, probably fewer. If the most powerful person on the planet can't do something about 40 people and Guantanamo Bay, which a is a blot on the American copybook and is costing over $3m per prisoner a year - he really shouldn't be president."

When Obama took office there were 242 detainees at Guantanamo. After Monday's announcement, of the 61 remaining, 19 have already been cleared for transfer.

Donald Trump's vow

November's presidential election is likely to help to determine the future of the prison, as Republican presidential candidate Donald Trump has vowed to fill Guantanamo with "bad dudes" should he win the White House.

Trump has said he would "bring back a hell of a lot worse than waterboarding", referring to a method of torture banned by the US government in 2007.

To date, just 10 of the prisoners have faced a criminal trial, including the "9/11 Five" led by Khalid Sheikh Mohammed who were accused of plotting the September 11, 2001 attacks.