Fatah activists say troops from the rival Palestinian movement Hamas broke up a Fatah gathering in the Gaza Strip, beating participants.
It was the most violent clash in months between Fatah and the Islamic militant Hamas, which seized Gaza from Fatah's leader, Palestinian President Mahmoud Abbas, in 2007.
The incident signaled continued hostility between Hamas and Fatah despite reconciliation attempts. It also suggested Hamas is on edge as it struggles to survive an Egyptian border closure.
Iyad al-Bozoum of the Gaza Interior Ministry said Sunday that troops broke up an indoor gathering of dozens of Fatah activists in the town of Khan Younis Saturday evening because they didn't have a permit. He says officers were attacked.
Fatah spokesman Hassan Ahmed says Hamas security beat and briefly detained participants.