UNITED NATIONS (AP) — U.N. Secretary-General Antonio Guterres is urging Morocco and the Polisario Front independence movement to refrain from actions that could affect the cease-fire in their 42-year conflict over the Western Sahara, pointing to an escalating dispute over a buffer zone.

In a report to the Security Council obtained Monday by The Associated Press, Guterres calls on the Polisario Front to withdraw from Guerguerat in the buffer zone on the Morocco-Mauritanian border. He urges Morocco to reconsider its refusal to send an expert mission as part of the U.N. effort to address questions raised by the Guerguerat situation.

Guterres says he was encouraged by steps his new personal envoy, Horst Koeler, has taken to relaunch political negotiations and urges additional steps by the parties, neighboring countries and other key players.