CAIRO — The leader of a pro-independence group in Western Sahara declared war Saturday on Morocco, shattering a three-decade-long cease-fire and threatening a full-blown military conflict in the disputed desert territory in northwest Africa.
The announcement came a day after Morocco launched a military operation in a United Nations-patrolled buffer zone after having accused the pro-independence group, the Polisario Front, of blocking access to neighboring Mauritania.
The eruption of hostilities in Western Sahara adds to the instability roiling some of Africa’s biggest countries, with a protracted war in Libya, long-simmering insurgency in Mali and an armed conflict in Ethiopia that threatens to become a civil war.
On Friday, Morocco said it had put up a “security cordon” on an important road connecting the country to Mauritania, which the Polisario considers illegal because the independence group says it was built in breach of the 1991 United Nations-brokered truce.
Both sides said late on Friday that they had exchanged fire but did not confirm any deaths or injuries. Nor did they specify how many combatants on each side were involved.
The Polisario Front accused Morocco of having shot at peaceful protesters whom the independence group said had been demonstrating against what it called the plunder of resources from the Sahrawi, the people who live in Western Sahara — all under the watch of the U.N. peacekeeping mission in the disputed territory.
The secretary general of the Polisario Front, Brahim Ghali, issued a decree announcing the “resumption of armed struggle in defense of the legitimate rights of our people.”
There was no immediate response from the Moroccan authorities on the announcement.
The decision to end the commitment to a cease-fire, which had defined the conflict for decades, now threatens to uncap the long-festering tension between the Moroccan kingdom and the liberation movement.
Western Sahara, a sparsely populated territory, was occupied by Morocco in 1975 after the Spanish colonial authorities withdrew. The Polisario, a socialist guerrilla movement formed in 1973, waged a war for independence and established the self-declared Sahrawi Arab Democratic Republic that received recognition from entities including the African Union.
The United Nations helped mediate a truce in 1991, with the understanding that a referendum would be held to decide whether the people of Western Sahara would choose independence or integration with Morocco. That referendum has yet to take place, mostly because the two sides cannot settle on who makes up the Indigenous people of the territory and should therefore be permitted to participate in the vote.
The conflict has left Morocco controlling about 80 percent of the disputed territory, leaving thousands of Sahrawis living in a protracted displacement situation near the Algerian town of Tindouf.
For years, the talks between the two sides have been vexed, with some observers worrying that terrorist groups might gain a foothold in the vast desert swathe and further undermine stability in the region. The negotiations have basically stalled since 2019, after the former special U.N. envoy resigned, citing health reasons.
The escalating tensions in recent days have drawn concerns from the United Nations, the African Union and nations in North Africa and across the Middle East. The U.N. secretary general, António Guterres, said in a statement on Friday that he was “determined to do everything possible to remove all obstacles to the resumption of the political process.”