Updated

The founder of Morocco's most powerful religious opposition movement and one of the few men to challenge the monarchy's quasi-religious status died Thursday at 87, according to an online statement by his group.

Abdessalam Yassine, founder of the Justice and Spirituality Movements, "has returned to God," the organization's guiding council said on its website. It added that the funeral will be held following Friday prayers at the capital Rabat's main mosque — a major honor.

"I am still in shock; he passed away this morning," said a tearful Nadia Yassine, his daughter, who also holds a leadership role in Al Adl wal Ihsan, the movement he founded in 1987.

There is no exact count of the size of the movement, but it is often estimated to number in the hundreds of thousands, drawing its strength from charity work and present all over the country.

The movement is officially banned and cannot participate in politics. Though it is tolerated, its members are often arrested.

Yassine was under house arrest for decades before he was released by the current king in 2000. He refused to recognize the king's religious title of Commander of the Faithful.

For a while the group joined the pro-democracy February 20 movement that emerged in 2011, adding its manpower to the demonstrations that rocked the country during the Arab Spring. With the election victory of a legal Islamist party in November, however, the group took a much lower profile.