Cairo mosque under siege

Supporters of deposed Egyptian President Mohammed Morsi are trapped in a mosque near Cairo's Ramses Square, as military and police forces keep the area surrounded.

A tense standoff continued early on Saturday morning at the Egyptian capital's Fateh Mosque.

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 interim officials say more than 1,000 Islamists were arrested on Friday, the AFP news agency reports.

"The number of Muslim Brotherhood elements arrested reached 1,004," the interior ministry said in a statement early on Saturday.

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.

TV stations are reporting that security forces had entered 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.

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.

The Muslim Brotherhood has been on the streets since the army deposed Morsi - Egypt's first democratically elected president - last month and installed an interim government.

On Wednesday at least 638 people died when the Brotherhood's two protest camps in Cairo were cleared, a move that sparked international condemnation.

Friday's protests - dubbed a "day of anger" - were called in response to Wednesday's bloodshed. Most of the latest deaths were in Cairo but about 25 were elsewhere, including 12 in Nile Delta cities.

Egypt's interim leaders have imposed a state of emergency with dusk-to-dawn curfews in the capital and other areas. The interior ministry says police have been authorised to use live ammunition "within a legal framework".

The army has blocked off all entrances to Tahrir Square - the focus of demonstrations that led to the toppling of President Hosni Mubarak in 2011.

Meanwhile, groups that support the army-backed interim government - the National Salvation Front and Tamarod - are calling for counter-demonstrations in response to the Muslim Brotherhood protests.