Four detainees held at the Guantanamo Bay US military prison have been repatriated to Afghanistan, the Pentagon said Saturday.

The Department of Defense said that the Afghan men -- Shawali Khan, Khi Ali Gul, Abdul Ghani, and Mohammed Zahir -- had been moved from the prison after a comprehensive review of their case.

"As a result of that review, which examined a number of factors, including security issues, these men were unanimously approved for transfer by the six departments and agencies comprising the task force," a Pentagon statement said.