Egypt's worst violence in months escalated the confrontation between political forces and the ruling military ahead of a landmark presidential election, as suspected army supporters attacked mainly Islamist protesters outside the Defence Ministry, sparking clashes that left at least 11 people dead.
Political parties swiftly blamed the ruling generals for the bloodshed and vowed the election must go ahead as planned to ensure the military's removal from power.
Egypt has been plagued by sporadic bouts of deadly violence since the ouster of long-time authoritarian leader Hosni Mubarak last year, but Wednesday's killings took on added significance, coming just three weeks ahead of the presidential election.
The killings also provided opponents of the military with more evidence the generals who took over from Mubarak are badly bungling the shift to democratic rule and acting much like their former mentor. "We blame the military council for the bloodshed," Islamist lawmaker Osama Yassin of the Muslim Brotherhood's Freedom and Justice Party said.
Around 1,000 protesters have been camped outside the Defence Ministry for days demanding an end to military rule. Most are supporters of disqualified presidential candidate Hazem Salah Abu Ismail, an ultraconservative Islamist barred from running because his late mother held dual Egyptian-US citizenship, making him ineligible under election laws.
However the violence, which broke out at dawn, prompted other factions to join in. Throughout the day, thousands marched to the site of the clashes in the Cairo district of Abbasiyah, protesting into the evening surrounded by armoured vehicles and lines of riot police.
The fundamentalist Brotherhood, Egypt's strongest movement, quickly moved to try to reap political gains from what has turned into a growing confrontation between it and the military. In a statement, it held the military responsible and warned that Egyptians would show "no mercy" if the generals did not meet what it called the revolution's demands.
The Brotherhood urged a new mass protest on Friday in Cairo's Tahrir Square to ensure the military hands over power by July 1 as promised. The Brotherhood has been frustrated that its domination of parliament - where it holds nearly half the seats - has not translated into political power because the military has kept executive rule in its own hands.
Their increasingly bitter quarrel has centred on the military-backed government led by Prime Minister Kamal el-Ganzouri. The Brotherhood has demanded that the military dismiss the government and allow the Islamist majority in parliament to form a new one.
The generals have so far ignored the calls, and in response Parliament Speaker Saad el-Katatni, a Brotherhood leader, suspended the chamber's sessions for a week on Sunday in protest.