The 35-year UN peacekeeping mission in Western Sahara will end after the Security Council failed to renew its mandate, the UN chief said on Sunday.

Morocco, which claims the Western Sahara as its ‌own, welcomed the decision, while its opponents in the Algeria-backed Polisario Front expressed concern.

The Polisario Front has sought an independent state in Western Sahara since former colonial power Spain left in 1976.

A peacekeeping mission, known as MINURSO, has been in place there ​since a UN-brokered ceasefire in 1991.

November 1 would mark the start of the mission’s “liquidation phase”, with assets transported back to troop-contributing countries, UN chief Antonio Guterres said in a statement.

The end of the peacekeeping mission comes ​a year after the UN Security Council adopted a US-drafted resolution that accepted Rabat’s plan to give the territory autonomy under Moroccan sovereignty as the “most feasible” solution to the conflict.

Russia, which abstained ​in last year’s vote, this year vetoed another US-backed resolution that would have ​cemented the UN’s preference for the Moroccan plan while scaling back the peacekeeping force.

The Security Council ‌then ⁠defeated a competing Russian resolution, leaving the mission to expire without a new mandate.

Besides monitoring the ceasefire, MINURSO was tasked with organizing a referendum that has never taken place due to disagreements over voter eligibility.

Morocco’s Foreign Minister Nasser Bourita told state ​media that the ​mission’s reference to ⁠a referendum – the “R” in its name – was an “anachronism”.

Rabat had been informed that Russia was going to block the US-drafted resolution, but ​saw it as “an opportunity to review certain rules of the ​game”, he ⁠said.

Morocco’s royal palace said the non-renewal was a “significant development” toward withdrawing the Western Sahara issue from the Security Council’s consideration.

Algeria’s Foreign Ministry on Saturday expressed “deep ​regret” over the non-renewal, blaming the “excessive bias” of the US toward Morocco’s position.

The Polisario said in a statement it was “concerned at the deadlock in the ​Security Council meeting.”