The most senior leader in Egypt’s Muslim Brotherhood, Mohammed Badie, has been arrested in Cairo.
Mr Badie, who was wanted over alleged incitement to violence and murder, has been temporarily replaced as “general guide” by his deputy, Mahmoud Ezzat.
In another development, Egypt’s ex-vice president Mohamed ElBaradei is to face trial on charges of breaching national trust after resigning last week.
Almost 900 people have been killed in the country since Wednesday.
Among them are 36 Islamist protesters who died in a prison van in Cairo on Sunday.