Mansoura (Egypt), Sep 27 (IANS/AKI): A senior leader of Egypt's Islamist Muslim Brotherhood movement, Safwat Khalil, has died in jail in the Nile Delta city of Mansoura, according to reports from the region.

Khalil, 59, who had cancer, died in custody Thursday shortly after a court ruling that ordered his release and that of 48 members of the Muslim Brotherhood.

Khalil's death in prison was confirmed by the Muslim Brotherhood which accused Egyptian authorities of "reluctance" to release Khalil even after the court order.

He was due to be freed Saturday after being arrested last month along with scores of Brotherhood supporters on charges of inciting violence and possession of weapons.

Khalil's health had recently deteriorated, especially after he was taken to court in a police van instead of an ambulance, according to one of his lawyers.

Thousands of people were reported to have taken to the streets to hold peaceful protests in Egypt days after a Cairo court Monday ordered that Brotherhood funds be seized.

Two days later, police stormed the headquarters of a Brotherhood newspaper and shut it down.

Egyptian authorities have unleashed a massive crackdown on Muslim Brotherhood leaders, rounding up hundreds of the group's senior and mid-ranking members, topped by its spiritual leader Mohamed Badie and deputies Khairat al-Shater and Rashad Bayoumi.

Brotherhood supporters had held sit-ins in Cairo demanding the reinstatement of elected Islamist president Mohammed Morsi who was deposed by the army July 3 after millions protested his rule.

Many hundreds of people, including nearly 100 soldiers and police, are said to have been killed in violent clashes between protesters and the army since Morsi's ouster July 3.