Egyptian riot police deployed on Saturday near the presidential palace after a night of clashes between security forces and petrol-bomb throwing protesters that killed one man and injured dozens.
The 23-year-old died of a gunshot wound as police used birdshot and tear gas on demonstrators who targeted the palace in rallies against Islamist President Mohamed Morsi late on Friday, a senior medical official said.
Fifty-three people were also injured, said the official, while the interior ministry reported 15 of its men wounded by birdshot.
Police said they arrested 20 people, and were filmed on television beating and dragging a naked man to an armoured vehicle, outraging Morsi critics who compared the incident to practices under deposed leader Hosni Mubarak.
On Saturday morning, there was no sign of any protesters, and streets in the area reopened to traffic, though they were littered with stones and other debris.
The smell of tear gas still lingered near the palace, its outer wall scrawled with graffiti reading: "Topple the regime" and "Freedom."
In the capital's iconic Tahrir Square, the situation was also calm after clashes in the latest day of protests that were also staged in other cities.
Interior Minister Mohammed Ibrahim ordered a probe to "hold accountable" the policemen who beat the naked protester, his office said.
The presidency said security forces would deal with violent protests with "utmost decisiveness" and that it would hold opposition groups found to have incited the clashes "politically accountable."
A statement on Morsi's Facebook page said the protesters sparked the violence by trying to break into the palace.
The opposition National Salvation Front, which supported Friday's protests, distanced itself from the violence and urged demonstrators to exercise "utmost restraint."
But hours before the violence erupted, NSF leader and Nobel Peace laureate Mohamed ElBaradei suggested unrest would persist if Morsi kept sidelining his opponents.
"Writing on wall: violence and chaos will continue until Morsi and co. listen to people's demands: new government, democratic constitution, independent judiciary," he wrote on Twitter.
People took to the streets in several cities in a show of opposition to Morsi and his Muslim Brotherhood after deadly unrest swept Egypt last week in the worst violence since Morsi was elected president in June.
The opposition coalition is thought to exert little influence over activists involved in clashes.
"The National Salvation Front represents only itself," said one masked protester outside the palace. "We are satisfied neither with Morsi nor the opposition."
Scores of protesters skirmished with riot police several hundred metres (yards) from Tahrir Square, witnesses said, and two were wounded by birdshot fired by police.
The clashes were less intense than in the past week's unrest which resulted in 56 deaths, mostly in Port Said, where violence erupted after 21 residents were sentenced to death on Saturday over football-related violence last year.
Thousands of people protested in the Suez Canal city on Friday calling for Morsi's removal, unfazed by a strong military presence, and similar marches took place in the Mediterranean port city of Alexandria.
The opposition accuses Morsi of betraying the revolution that toppled Mubarak two years ago and took him to the presidency.
The NSF joined rival Islamists Thursday in condemning violence and supporting efforts for a national dialogue, while insisting on a unity government and the amendment of the Islamist-drafted constitution, which polarised the nation when it was passed in December.
The crisis has sapped the popularity of Morsi -- who won the June election with a slender majority -- and complicated negotiations for a crucial $4.8-billion IMF loan that could help bail out the teetering economy.