A U.S. appeals court on Monday blocked President Donald Trump's administration from immediately transferring an American citizen accused of being an Islamic State member from military custody in Iraq to an unidentified country, apparently Saudi Arabia.

The man, who holds dual American-Saudi citizenship and whose name has not been released, was captured in Syria and had been held in Iraq without legal representation until the American Civil Liberties Union intervened on his behalf in U.S. federal court last October.

The administration was seeking to transfer custody of the man even though U.S. courts had not resolved the legal challenge launched to win his release. A three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit ruled 2-1 on Monday to uphold U.S. District Judge Tanya Chutkan's ruling last month that had stopped the planned transfer.