United Nations Secretary General Antonio Guterres (C) stands on stage for the group photo at the 14th ASEAN-United Nations Summit during the 44th and 45th Association of Southeast Asian Nations (ASEAN) Summits in Vientiane on October 11, 2024. [AFP]

Morocco's Foreign Minister Nasser Bourita said Monday that a recent proposal by a United Nations envoy to partition the disputed territory of Western Sahara was "unacceptable", citing past rejections of similar plans.

In a closed session of the UN Security Council last week, Western Sahara envoy Staffan de Mistura proposed dividing the territory between Morocco and the pro-independence Polisario Front to resolve a decades-old conflict.

Bourita said de Mistura had already proposed a visit to Morocco in April, which the kingdom had rejected.

"Morocco has not and will not even accept hearing the proposal, because it contradicts the kingdom and Moroccans' principled position that the Sahara is Moroccan," Bourita told a press conference in the capital Rabat.

Western Sahara is largely controlled by Morocco but the Polisario Front -- which is backed by Morocco's regional rival Algeria -- has campaigned for independence for the territory since before colonial ruler Spain pulled out in 1975.

It is considered a "non-autonomous territory" by the United Nations.

Rabat, which controls some 80 per cent of the vast expanse, advocates a plan for limited autonomy for Western Sahara under Moroccan sovereignty.

The Polisario Front is calling for a referendum on self-determination under the aegis of the UN, which had been planned when a ceasefire was signed in 1991 but never implemented.

De Mistura, a 77-year-old Italian-Swedish diplomat, has been UN Secretary-General Antonio Guterres' personal envoy for the territory for the past three years.

Bourita said Morocco had also rejected a similar plan in 2002 when former UN envoy to Western Sahara James Becker had brought it "on the proposal of Algeria".

"Morocco does not negotiate its sovereignty over the Sahara," he said, calling the issue "a regional dispute with a neighbouring country that objects to Morocco's sovereignty over its land".

Algeria broke off diplomatic relations with Morocco in 2021, partly over the issue.

In 2020, the United States recognised Morocco's annexation of Western Sahara in return for Rabat's normalising ties with Israel.

Bourita called for "round table" talks to be held to reach a "political solution" to the conflict -- within Moroccan sovereignty.

The press conference was held with Estonian Foreign Minister Margus Tsahkna, who in a joint statement said that Estonia considers Morocco's autonomy plan was "a good, serious and credible basis for a solution".