Palestinian Prime Minister Mahmoud Abbas has challenged his parliament to back him - or face his resignation.

In a speech to MPs, who are reviewing his first 100 days in office, Mr Abbas publicly admitted rifts with Palestinian leader Yasser Arafat - and said they must be corrected.

"Either provide the possibility of strong support for carrying out [the mandate] or you can take it back," he said, while stopping short of demanding a formal vote of confidence.

Mr Abbas, also known as Abu Mazen, called on the United States to lift its boycott of Mr Arafat - "the elected, legitimate, constitutional and historical president of the Palestinian people". Washington has refused to negotiate with Arafat, whom it accuses of trying to undermine the roadmap for peace.

Mr Arafat was not present at the meeting - he remains isolated in his Ramallah headquarters.

But his supporters forced the prime minister to enter the parliament building through a back door.

Some tried to force their way into the building. Masked men carrying swords and clubs spray-painted a slogan on the wall, "We want Abu Mazen's government to fall" and signed: the Al-Aqsa Brigades - linked to Mr Arafat's Fatah movement.

Echoing a similar line by Mr Arafat, the prime minister blamed Israel for the collapse of the ceasefire declared by Palestinian militants at the end of June.

But he urged Palestinians not to give in to the "spiral of action and reaction" and not to take unilateral action that would undermine Palestinian national unity and further isolate their case.

Leading Israeli Government ministers consider Mr Arafat to be a "major obstacle" for the Palestinian prime minister and for the whole political process.

The PA government's efforts to control militant groups which launch attacks on Israel have so far been largely confined to measures such as freezing the bank accounts of Islamic charities with alleged links to Hamas.

Mr Arafat largely still controls the PA's security services.

And Mr Abbas wants greater control of the Palestinian security forces to be able to tackle armed groups responsible for suicide attacks against Israelis.

Mr Abbas appointed Saeb Erekat as chief Palestinian negotiator in talks on the roadmap. Erakat said earlier that Abbas was expected to reappoint him.

He held the then newly created negotiations portfolio for only two weeks when he called it quits after he was not invited to participate in a high-level meeting with Israel.

He previously led Palestinian teams in negotiations with Israel before the September 2000 outbreak of the uprising and is considered closer to Arafat, whom Israel and the United States are trying to sideline, than to Abbas.

But in a further reminder that Mr Abbas has failed to rein in Palestinian militants, an Israeli was shot dead in the West Bank on Thursday morning, Israeli security sources said.

The Israeli was shot near the West Bank town of Jenin and died en route to hospital, the Israeli daily Haaretz reported. It said the al-Aqsa Martyrs' Brigades and Islamic Jihad had admitted carrying out the attack.