World condemnation widened for the bloody crackdown on Morsi's supporters, including an angry response from President Barack Obama, who canceled joint US-Egyptian military maneuvers.

Violence spread Thursday, with government buildings set afire near the pyramids, policemen gunned down and scores of Christian churches attacked. As turmoil engulfed the country, the Interior Ministry authorized the use of deadly force against protesters targeting police and state institutions.

The Muslim Brotherhood, trying to regroup after the assault on their encampments and the arrest of many of their leaders, called for a mass rally on Friday in a challenge to the government's declaration of a month long state of emergency and a dusk-to-dawn curfew.

At least 638 people were confirmed killed and nearly 4,000 wounded in the violence sparked when riot police backed by armored vehicles, snipers and bulldozers smashed the two sit-ins in Cairo where Morsi's supporters had been camped out for six weeks to demand his reinstatement. It was the deadliest day by far since the 2011 popular uprising that overthrew autocratic ruler Hosni Mubarak and plunged the country into more than two years of instability.

The Health Ministry said that 288 of those killed were in the largest protest camp in Cairo's Nasr City district, while 90 others were slain in a smaller encampment at al-Nahda Square, near Cairo University. Others died in clashes that broke out between Morsi's supporters and security forces or anti-Morsi protesters elsewhere in the Egyptian capital and other cities.

Mohammed Fathallah, the ministry spokesman, said earlier that the blood-soaked bodies lined up in the El Iman mosque in Nasr City were not included in the official death toll. It was not immediately clear if the new figures included the ones at the mosque.

Inside the mosque-turned-morgue, the names of the dead were scribbled on white sheets covering the bodies, some of them charred, and a list with 265 names was plastered on the wall. Heat made the stench from the corpses almost unbearable as the ice brought in to chill the bodies melted and household fans offered little relief.

Weeping relatives filled the mosque courtyard and spilled into the streets. In a corner, a woman cradled the head of a slain man in her lap, fanning it with a paper fan. Nearby, an anguished man shouted, ``God take revenge on you el-Sissi!'' a reference to the powerful military chief, Gen. Abdel-Fatah el-Sissi. (AP)