The army deployed around Cairo's Defence Ministry to deter protesters after a soldier died and 373 people were wounded in clashes during demonstrations against Egypt's ruling generals, less than three weeks before a presidential vote.
Cleaners swept up debris after Friday's violence in the Abbasiya district where streets were calm but strewn with rocks and other projectiles hurled by protesters at troops, who fired teargas and charged the crowd to drive them from the ministry.
It was the second time in a week that clashes had erupted near the ministry where protesters had gathered to vent their anger over the army's handling of Egypt's troubled transition from army rule to civilian government. Eleven people were killed on Wednesday.
The New York-based Committee to Protect Journalists said at least 18 journalists had been assaulted, injured or arrested while covering the clashes.
"We call on the ruling Supreme Council of the Armed Forces to identify the attackers and bring them to justice immediately, as well as to release journalists in custody," Mohamed Abdel Dayem, CPJ's Middle East and North Africa programme coordinator, said in a statement issued late on Friday.
A presidential election, which starts on May 23-24, will choose a replacement for Hosni Mubarak, who was toppled in February last year. Generals have governed since then but their rule has been punctuated by violence and political bickering.
Many protesters who gathered near the ministry were ultra-orthodox Salafi Muslims furious that a sheikh they backed for president was disqualified from the race. Liberals and others were also there, accusing the army of seeking to manipulate or delay the vote.
The military has dismissed those allegations, insisting it will stick to its timetable of handing over power to a new president by July 1, or even earlier in the unlikely event of an outright winner in the first round of voting this month.
"Our mission ends with a successful handover of power, and we will not let anyone change the declared schedule," an army source told the website of the state-owned Al-Ahram daily.
The authorities detained more than 170 people in connection with Friday's violence after the army warned protesters a day earlier it would not tolerate threats to any of its installations. The funeral for the soldier killed was scheduled for later on Saturday, state media reported.
Troop carriers and soldiers formed cordons protecting the area around the ministry and deployed at nearby installations belonging to the army, which for the first time in six decades faces the prospect of a president who has not been plucked from its senior ranks.
Mubarak, like his predecessors since the king was toppled in 1952, had been a top military officer before becoming president.
Many of the protesters have called for the army to step aside sooner than planned. Scenes of troops beating protesters with sticks in anti-army demonstrations in recent months have angered many Egyptians, who expect the generals to wield their influence from behind the scenes even after a formal handover.
But many other Egyptians are equally frustrated at the protesters, accusing them of stirring up trouble on the streets and helping drive the economy to the brink of a balance of payments crisis. The nation's foreign reserves have plunged.
"The army is our leader in this period and they said a million times that they don't want to stay in power. We have elections in a few days, so I don't understand what all yesterday's fuss and violence was all about," said Essam Mohamed, 51, a government office worker in the Abbasiya area.
The presidential race broadly pits Islamists against more liberal-minded candidates who at one time or another served in Mubarak's administration.
The two-front runners are Abdel Moneim Abol Fotouh, an Islamist who has won the backing of a broad range of voters ranging from liberals to hardline Salafi Islamists, and Amr Moussa, the former head of the Arab League and one-time foreign minister. The Muslim Brotherhood is also fielding a candidate.