Egyptian police have clashed with hundreds of anti-government protesters in Cairo's Tahrir Square, leaving several people injured, BBC reported.
Riot police fired tear gas to try to disperse the protesters, many of whom hurled stones at the police lines.
Tahrir Square was the epicentre of February's revolt that led to President Hosni Mubarak being toppled.
Many of the protesters were calling for the prosecution of former officials to be speeded up.
As dawn broke, stones and broken glass littered the streets around Tahrir Square. Witnesses said it was worst violence in the square for weeks.
The confrontation started on Tuesday when police cleared a sit-in outside the state TV building by families of those killed in February's uprising, activists said.
The protesters later regrouped outside the interior ministry and clashes broke out with police.
Fighting escalated and moved to Tahrir Square where lines of riot police carrying shields sealed off the main streets and dozens of security vehicles parked in side streets.
As volleys of tear gas rained down, injured demonstrators were seen lying on the ground, some dazed and bloodied.
"The people want the fall of the regime," some of the demonstrators chanted.
Ahmed Abdel Hamid, 26, who was among the protesters, said people were angry that court cases against senior officials were being delayed.
Last week, Egypt's former Trade Minister Rachid Mohamed Rachid was sentenced to five years in prison in absentia for embezzling public funds.
Earlier this month, former Egyptian Finance Minister Yussef Boutros Ghali was sentenced to 30 years in prison in absentia, also on corruption charges.
Former President Mubarak, in custody at a military hospital, is due to go on trial on 3 August alongside his sons, Alaa and Gamal.
Mr Mubarak is charged with the deaths of protesters during Egypt's uprising.