Head of the International Union for Muslim Scholars (IUMS) Ahmed Raissouni resigned on Sunday amid uproar over his recent remarks on the disputed Western Sahara region.
Raissouni sparked controversy earlier this month when he said Mauritania should be part of Morocco.
"I previously mentioned that even Mauritania's existence is a mistake," Raissouni said in a TV interview when asked about the Western Sahara issue.
"This is a colonial construct. The question of the Sahara, and the question of Mauritania. But the Mauritania issue was acknowledged by Morocco, and at any rate, it's left to history to decide on in the future."
His comments drew fire from several Mauritanian groups amid calls for the scholar to apologize. The IUMS, for its part, said Raissouni's comments don't represent the views of the pan-Islamic body.
In a statement on Sunday, Raissouni said his resignation "comes from his adherence to his firm positions and views, which do not accept compromise, and in order to exercise his freedom of expression without conditions or pressure."
The Doha-based union said in a statement that it had accepted Raissouni's resignation "in response to his desire to step down."
Western Sahara is an area along Africa's Atlantic coast that has a population of about 600,000 residents, according to UN estimates. It was colonized by Spain in the 19th century and annexed in 1975 by Morocco.
Rabat insists on its right to the Western Sahara region, but has proposed a self-rule system under Moroccan sovereignty.
The pro-independence Polisario Front, for its part, demands that a popular referendum be held in Western Sahara to decide the region's political fate -- a proposal backed by Algeria.