Egyptian military police used force to break up an "iftar" traditional evening meal for the Muslim holy month of Ramadan in Cairo's Tahrir Square on Friday, witnesses said.
Activists and families were taking part in the iftar which breaks the daytime fast during Ramadan.
"We were about 150 people, gathered near Omar Makram mosque, when military police with batons dispersed us and started hitting us," a participant, Ahmed Fares, told AFP.
"After the iftar, some people started calling for the hanging of (ousted president Hosni) Mubarak. The police intervened with batons, forcing us to run away down into the metro station," said activist Ahmed Naim.
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A woman also at the scene said an officer told her that security forces took action because some participants had hurled rocks.
According to another militant, Nur Nur, several arrests were made.
On Monday, security agents fired shots in the air and used their batons in a clash with dozens of protesters who had refused to leave Tahrir Square, a day after most activists suspended a daily sit-in.
The government said "several thugs" were arrested.
Activists have said they will return in large numbers to the square, which was the epicentre of mass street protests that toppled Mubarak in February, to push for reforms once Ramadan is over.