Its members tend to be younger than those of other Fatah factions, often having grown up in the post-Oslo era.

Some attribute this to the discipline and better training of Hamas's fighters, as most of the casualties were from the Fatah faction.

But Mr. Arafat and the central committee of his Fatah faction blocked the appointment.

It was through the Fatah faction that he took over the PLO in 1969.

Israel promised a response to the attack here, responsibility for which was claimed by a group linked to Mr. Arafat's own Fatah faction.

But it includes figures from Mr. Abbas's Fatah faction and several independents.

His Fatah faction now lies beaten, its monopoly on official power ended.

In March, Hamas joined with the more mainstream Fatah faction in a unity government.

Mr. Arafat's rising support did not seem to be helping his Fatah faction, though.

At least five of the dead were militants linked to the Fatah faction, local medics and the army said.