Hundreds of Sudanese asylum seekers slated for deportation have spent a night near Jordan’s international airport, as the U.N. refugee agency urged Jordan not to send them back to Sudan.

Agency spokeswoman Aoife McDonnell said Thursday that “we are gravely concerned about these people.” She says the potential deportations “go against the principle of no forced return” enshrined in international law.

The agency says majority of some 3,500 Sudanese in Jordan are from the troubled Darfur region where they risk being persecuted.

Government spokesman Mohammed Momani said “logistics are being worked out” concerning the Sudanese. He did not say if Jordan will go ahead with plans to deport about 800.

On Wednesday, Jordanian troops tore down a Sudanese tent camp and took its residents to the airport in buses.