Mohamed Abdelaziz, the secretary general of the Polisario Front, a movement fighting for independence of the largely desert region of Western Sahara, has died.
Abdelaziz, in his late sixties, died on Tuesday afternoon after a long battle with illness, the official website of the separatist movement said.
The movement ordered a 40-day mourning period, after which a new secretary-general will be chosen, it added.
"This is a great loss for the Sahrawi people," Polisario Front official Mohammed Keddad told the AFP news agency.
"He sacrificed his life for the liberation of Western Sahara. He embodied the wisdom and a sincere and firm commitment to its liberation," he added.
Khatri Abdouh, the head of the Saharawi National Council and a long-time aide of Abdelaziz, was appointed as interim Polisario Front leader.
Abdelaziz had led the Polisario Front since 1976, three years after the group was founded to fight for independence for the former Spanish colony.
Samir Bennis, the editor-in-chief of the online newspaper Morocco World News, told Al Jazeera that Abdelaziz's death would have little impact on attempts to end the conflict.
"Abdelaziz's death will not change anything between Morocco and Algeria. What might bring change is what happens next in Algeria," Bennis said.
"Abdelaziz Bouteflika [the Algerian President] has been sick for many years, and any change will depend on who rules Algeria. The Polisario is not the master of its destiny. Decisions are not made in the Tindouf camps [Sahrawi refugee camps], but in Algiers."
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Morocco has controlled most of Western Sahara since 1975 and claims sovereignty over the sparsely populated stretch of desert to its south, which has offshore fishing and phosphate reserves.
Morocco's annexation of Western Sahara prompted an armed struggle by the Polisario Front backed by Morocco's neighbour, Algeria.
Tens of thousands of Sahrawi civilians were forcibly expelled by the Moroccan government, and the Polisario Front's leadership was forced into exile in Algeria.
The UN brokered a ceasefire in 1991, but talks to resolve the 41-year dispute have so far failed to yield a breakthrough.
Senia Bachir, a Sahrawi activist, told Al Jazeera that the Polisario Front would continue its fight for self-determination and independence following Abdelaziz's death.
"It's been over 40 years of struggle to attain this fundamental right and the Polisario Front, now more than ever, will continue to champion that cause until the complete liberation of our country, Western Sahara," she said.
The Polisario Front has been demanding a referendum offering full independence, while Morocco has so far only been willing to offer limited autonomy under Moroccan sovereignty.
Source: Al Jazeera and agencies