The United Nations says it has closed a military liaison office in the disputed Western Sahara after Morocco gave the U.N. observers there 72 hours to leave to protest remarks by U.N. Secretary-General Ban Ki-moon.

It follows Morocco's expulsion of 84 international civilian staff members with the U.N. peacekeeping mission in the Western Sahara.

Morocco annexed Western Sahara in 1975 and fought the Polisario Front independence movement until the U.N. brokered a ceasefire in 1991, which the peacekeeping force has been monitoring. It has tried unsuccessfully since then to organize a referendum on Western Sahara's future.

U.N. deputy spokesman Farhan Haq said Tuesday that the Dakhla liaison office, which dealt with the Moroccan army in the area, was closed Monday and the three military observers were relocated to another site.