An Egyptian security official says 650 people, mostly backers of ousted President Mohammed Morsi, have been detained for allegedly trying to storm a military facility, an incident the military claims sparked violence that left more than 50 pro-Morsi protesters dead.
The detainees were largely pro-Morsi protesters seized during clashes early Monday outside the Republican Guard headquarters. Protesters and Morsi's Muslim Brotherhood deny any attack took place on the headquarters, saying troops opened fire on their sit-in nearby as the protesters finished dawn prayers.
The security official said Syrian and Palestinian nationals were among those arrested. The official spoke on condition of anonymity because he was not authorized to talk to the press.
Egypt's Muslim Brotherhood has called nationwide protests against what it calls a military coup against democracy.