More Guantanamo releases likely before Jan 20 - White House

"I am not able to speak to any specific detainee transfers between now and Jan. 20 other than to confirm for you that there are likely to be some," White House spokesman Josh Earnest said at a Thursday news briefing.

Obama's final push to shrink the inmate population aims to send as many as 19 prisoners to at least four countries, including Italy, Oman and the United Arab Emirates, before Donald Trump is sworn in on Jan. 20. The Republican president-elect has pressed to halt such releases and has vowed to keep Guantanamo open.

On Wednesday, U.S. officials said there were plans to transfer four detainees from Guantanamo to Saudi Arabia within 24 hours.

Asked about the risk of detainees turning to militant activity against the United States, Earnest said only nine of 183 detainees transferred since Obama took office have been confirmed by the intelligence community as re-engaging in the fight.

He compared that to a 21 percent rate of return to militant activity of inmates released before 2009.

Earnest credited the low number to a process that required a variety of agencies to certify that appropriate security requirements were in place before an individual was transferred.

If the final transfers go according to plan, only about 40 prisoners will remain at Guantanamo, despite Obama's pledge to close the controversial facility at the U.S. naval base in Cuba.

Meanwhile in RIYADH, three inmates from the US military prison in Guantanamo Bay arrived in Saudi Arabia on Thursday, after the White House rejected President-elect Donald Trump's demand for a freeze on transfers.

The three prisoners landed at a terminal normally reserved for royals at the Riyadh international airport.

The relatives of one inmate were waiting for his arrival. They identified him as Mohammed Bawazir, a Yemeni, and said he had been held for 16 years at the US facility in Cuba.

The identity and nationality of the other two prisoners was not immediately clear. The three were among 59 prisoners remaining at the detention centre in Cuba.

Before Thursday's transfer, around 20 of the remaining prisoners had been cleared for removal. But finding countries to take them has often proven time-consuming.

Only a handful of those who remain have started moving through military tribunals, including the alleged plotters of the 9/11 attacks.

Many of the others are in legal limbo - not charged but deemed too dangerous to release.

Fifteen of the 19 Al-Qaeda hijackers who carried out the attacks against the United States on Sept 11, 2001 were Saudi. But Riyadh denies any ties to the plotters who killed nearly 3,000 people.

In recent months, Obama has authorised a flurry of transfers of prisoners to other countries including Yemen and Saudi Arabia - prompting outrage from Republicans each time.

In April, nine Yemeni inmates were transferred from Guantanamo Bay to Saudi Arabia, the first time the kingdom received any inmates from the facility.

The move followed years of negotiations with the Saudi government, and the former inmates were to participate in a Saudi rehabilitation and de-radicalisation programme.

Yemen's civil war meant those inmates could not be sent to their home country.

Because the Guantanamo Bay naval base is on Cuban and not US soil, it is not subject to the same federal laws and legal processes as the United States.