Gaza Strip ? Tens of thousands of Fatah supporters packed Gaza’s main soccer stadium Sunday in a show of strength to boost the movement in its increasingly violent struggle against the Islamic militant group Hamas.

The demonstration came as masked Fatah gunmen released a video of a kidnapped Hamas official, threatening to expand attacks against Hamas if it rejects calls to disband its militia in the Gaza Strip. The video, reminiscent of scenes in Iraq, marked a new tactic in the latest spate of Palestinian factional violence.

The stadium demonstration marked the 42nd anniversary of the founding of Fatah by the late Yasser Arafat, but was meant to send a clear message to Hamas, which has defiantly rejected Fatah’s calls to outlaw the Gaza militia.

Fatah and Hamas have been locked in a bloody struggle for control of the Palestinian government since the Islamic group won parliamentary elections last year. The victory ended four decades of Fatah political domination, though the group still controls the powerful Palestinian presidency.