The US has hosted representatives of Morocco, Mauritania, Algeria and the Polisario Front, the Sahrawi national liberation movement, in Madrid for secret talks to discuss the occupied Western Sahara.

High-level delegations, each composed of three members led by their respective foreign ministers, met at the residence of the US ambassador in the Spanish capital on Sunday.

The talks were overseen by Massad Boulos, Donald Trump's senior adviser on African affairs, accompanied by Michael Waltz, the US ambassador to the United Nations, and the personal envoy of the UN Secretary-General for Western Sahara, Staffan de Mistura.

The meeting, which was supposed to remain confidential, was revealed by Spanish newspaper El Confidencial's journalist Ignacio Cembrero on Saturday.

According to Cembrero, the framework for the discussions was Morocco's autonomy plan for Western Sahara, which was adopted by the UN Security Council last year.