Egyptian police fired tear gas on Saturday at dozens of demonstrators throwing rocks outside an Alexandria courthouse where the city's ex-security chief and other officers are on trial for the killing of protesters during the country's 2011 uprising.
Mohammed Ibrahim and five police officers are accused of using excessive violence to put down the 18-day revolt.
Thousands of protesters have taken to Egypt's streets over the past two years to demand justice for those killed by the police and military.
Saturday's clashes broke out as human rights activists and family members of those killed in Alexandria protested outside the court.
At least three demonstrators and three police officers were hurt.
Clashes erupted again later in the day after Judge Mohammed Hammad Abdel-Hadi barred the prosecution from calling witnesses.