Morocco's government threatened to take control of U.N.-monitored buffer zones in Western Sahara amid concerns that the mission is failing to keep out Polisario Front independence fighters. The warning Sunday came as the U.N. is preparing a report this week on whether to extend its 27-year-old peacekeeping mission for Western Sahara, a territory claimed by both Morocco and the Polisario.

Moroccan Foreign Minister Nasser Bourita said Sunday that the Polisario recently moved members to the U.N.-controlled areas of Bir Lehlou and Tifariti. He also said Polisario members are again entering the Guerguerat area near the Mauritanian border, despite a U.N.-brokered deal to leave after tensions erupted there in 2016.

"If the U.N., its secretary general and the Security Council are not ready to put an end to these provocations, Morocco will have to act out its responsibility and intervene in the buffer zones," Bourita told reporters after an emergency parliament session to address Western Sahara. Bourita said Morocco has alerted the Security Council to its plans to step in the deserted land, but declined to specify what kind of intervention or when it would begin. Interior Minister Abdelouafi Laftit said, "Morocco is ready to do everything to preserve its Sahara."

Morocco annexed Western Sahara, a former Spanish colony, in 1975 and fought the independence-seeking Polisario Front. The U.N. brokered a cease-fire in 1991 and established a peacekeeping mission to monitor it and to help prepare a referendum on the territory's future that has never taken place. The Saharans' envoy to Algeria, Abdelghafour, said Polisario members in the buffer zones are under surveillance by U.N. forces, and accused Morocco of violating the cease-fire.