Sporadic clashes broke out overnight between protesters demanding the resignation of Egypt's Islamist President Mohamed Morsi and security forces outside the presidential palace, witnesses said on Sunday.
There were no immediate reports of casualties from the confrontations which follow violent clashes on Friday outside the presidential palace that left one person dead.
Late on Saturday several hundred mostly young protesters again gathered outside the compound and threw stones and petrol bombs at its walls, an AFP correspondent said.
One protester said they were there to pay homage to the young man killed on Friday, and they chanted "Leave!" and "The people want the regime to fall!" -- slogans used two years earlier to oust veteran president Hosni Mubarak.
In Friday's clashes, a 23-year-old was shot dead and 91 people were injured, a medic said, and the interior ministry said 15 of its men were wounded by birdshot.
Security forces deployed outside the palace grounds fired tear gas late on Saturday when a group of protesters tried to storm one of the gates, the witnesses said, but republican guards inside the compound did not intervene.
"We no longer respond to provocation from certain protesters outside the palace," the commander of the guards, General Mohammed Ahmad Zaki, was quoted as saying by the state-run MENA news agency.
The main opposition National Salvation Front (NSF), meanwhile, called for the resignation of Interior Minister Mohammed Ibrahim after a video showing a naked man being beaten by police went viral on the Internet.
The beating was "an inhumane spectacle... no less ugly than the killings of martyrs, which is considered a continuation of the security force's programme of excessive force," the opposition bloc said.
Ibrahim has ordered a probe to "hold accountable" those responsible and will resign if "that's what the people want," his office said.
The presidency also scrambled to contain fallout from the footage.
A statement said the presidency was "pained by the shocking footage of some policemen treating a protester in a manner that does not accord with human dignity and human rights" but described the incident as an "isolated act."
Prosecutors say Hamed Saber, a 50-year-old construction painter, was found carrying petrol bombs.
Saber said on television that he had been set upon and stripped by protesters and that the police had saved him, but his daughter Randa disputed the account and said on television: "He's lying; he's scared."
A nephew of Saber added: "He is lying because there is a lot of pressure on him."