JERUSALEM (Reuters) - Palestinian militants shot dead a foreign worker in the West Bank on Monday, calling into question a cease-fire with Israel that their leaders declared under a fragile U.S.-backed Middle East peace plan.

The ambush occurred hours after Israel pulled forces out of parts of the Gaza Strip (news - web sites), launching a disengagement process buoyed by the truce announcement of Islamist militant factions and Palestinian President Yasser Arafat (news - web sites)'s Fatah (news - web sites) movement.

Fatah officials said armed groups within the movement would comply with the pact. But a spokesman for Fatah's main militant faction, the al-Aqsa Martyrs Brigades, said it never approved the deal and claimed responsibility for the shooting.

"We are not committed to this so-called truce and we will continue to fight the (Jewish) settlers and the Israeli military inside the occupied territories," the official told Reuters.

The attack, on a passing truck near the settlement of Shaked in the northern West Bank, raised questions about a follow-up deal for an Israeli withdrawal from Bethlehem in the south of the territory reported by Palestinian security minister Mohammad Dahlan. [...]