A United Nations official is warning that the U.N. peacekeeping mission in the disputed Western Sahara will have to shut down unless Morocco reverses its unprecedented expulsion order.

The official, who is familiar with the Western Sahara controversy, said Secretary-General Ban Ki-moon wants the Security Council to take action to protect the mission, known as MINURSO.

This would also send a message to other countries hosting U.N. peacekeeping operations that such actions won't be tolerated, the official said Wednesday, speaking on condition of anonymity because of the sensitivity of the issue.

Morocco ordered 84 civilian staffers to leave and closed a military liaison office to protest Ban's use of the word "occupation" in describing the status of Western Sahara during a recent visit to camps in Algeria for Western Sahara refugees.