Fifteen detainees held at the US naval base at Guantanamo Bay have been freed, the Pentagon has said.
The prisoners were not identified beyond their nationalities
They come from a variety of countries, including Afghanistan, Turkey, Tajikistan, Sudan, Iraq, Jordan and Yemen, it added.
The prisoners, who were not identified, were flown out to their home countries in the past few days, an official said.
It brings to 146 the number of men to have left Guantanamo, for release or for detention by their own governments.
"The decision to transfer or release a detainee is based on many factors, including whether the detainee is of further intelligence
value to the United States and whether he is believed to pose a threat to the United States," a defence department statement said.
"The circumstances in which detainees are apprehended can be ambiguous, and many of them are highly skilled in concealing the truth," it added.
Sudanese television reported that two of its nationals arrived in Khartoum on Friday morning.
The Pentagon said 595 prisoners are still being held.
Most of them were captured in 2001, during the early months of the US-led war in Afghanistan.
Human rights group have challenged the legal basis for their detention without charge.