Egyptian security forces are preparing to besiege supporters of deposed president Mohamed Morsi who are gathered in Cairo protest camps.
Egypt has been polarised since the army deposed Morsi after mass protests.
Western and Arab mediators and some senior members of the Egyptian government have been trying to persuade the army to avoid using force to disperse the protesters, fearing a new wave of bloodshed.
International news agencies are quoting unnamed Egyptian officials saying forces would begin to surround the camps on Monday.
Egypt\’s interim leaders had warned several times they would dismantle the sit-ins after the Eid al-Fitr holiday which ran through Sunday.
Senior government sources told the pan-Arab Asharq Al-Awsat newspaper the plan will be carried out gradually in an attempt to keep casualties among Mr. Morsi\’s supporters to a minimum.
A brief power cut early Sunday at the main sit-in outside the Rabaa al-Adawiya mosque struck panic among the pro-Morsi demonstrators.
The government later issued a statement saying the blackout at Rabaa al-Adawiya in northeast Cairo was unintentional.
Thousands rallied on Sunday to demand Morsi\’s reinstatement, amid last-ditch efforts for reconciliation ahead of the threatened crackdown.
A large convoy of cars carrying pictures of the deposed president beeped their horns as they drove through a neighbourhood in east Cairo.
Pro-Morsi supporters have said they will not leave the sit-ins until the president, ousted in a popularly supported coup July 3, is reinstated.
More than 250 people, most of them Morsi supporters, have been killed in clashes since the military deposed Egypt\’s first democratically elected leader following mass protests demanding his resignation.
Also on Sunday, the army said it had killed at least eight suspected militants in a strike in the Sinai peninsula.
According to a statement from an army spokesman, those targeted were involved in the killing of 16 Egyptian border guards in August last year.
The Sinai region has become increasingly lawless since President Mubarak was ousted in 2011.