Egyptian security forces are trying to end a siege at a Cairo mosque where hundreds of Muslim Brotherhood supporters spent the night barricaded. The tense stand-off followed a day of bloody clashes on Friday in which more than 80 people died. Egypt is in turmoil after protest camps in Cairo were cleared on Wednesday with the loss of hundreds of lives. The Brotherhood, which backs deposed President Mohammed Morsi, has called for a week of daily rallies. Meanwhile, Egypt’s interior ministry said in a statement that 1,004 “Muslim Brotherhood elements” had been arrested on Friday. The ministry said 558 of the arrests took place in Cairo. On Saturday, police surrounded the al-Fath mosque in Cairo’s Ramses Square, where Morsi supporters were holed up. Security forces have entered the mosque to negotiate with the Islamist protesters to persuade them to leave. Live television pictures showed security forces in riot gear on the steps outside, but with no sign of violence. The BBC’s Bethany Bell in Cairo says those inside are worried about the possibility of arrests and more violence. They want the security forces to move away from the area before they leave the mosque. Ramses Square was a focal point of Friday’s clashes and the mosque was quickly filled with the dead and injured – as well as those fleeing the violence. Witnesses said nearly 1,000 people were trapped inside. Security officials quoted by the official Mena news agency said “armed elements” had opened fire from inside the mosque. Separately, health ministry officials in Alexandria said the death toll in clashes there on Friday had risen to 21