Militants from a group linked to president Mahmud Abbas's secular Fatah faction ransacked dozens of offices linked to Hamas including charities, a school and television and radio stations in the city of Nablus, witnesses said.

Gunmen from the Al-Aqsa Martyrs' Brigades also stormed the parliament building in Ramallah in search of Hamas members, while a top commander ordered Hamas militants to turn over their weapons.

The violence in the Israeli-occupied territory erupted a day after Hamas's bloody capture of the Gaza Strip, where masked Hamas fighters were roaming the streets of what is now an Islamic enclave sandwiched between Israel and Egypt.

Abbas, bolstered by Western and Arab backing in the deadly standoff, named a new moderate prime minister Salam Fayyad to head his emergency cabinet on Friday, in the hope of an end to a crippling Western aid boycott.

The new cabinet was set to be unveiled on Saturday, effectively sealing the divide of the Palestinians and making their aspirations of an independent state an ever more distant dream.

Hamas's takeover of Gaza, branded a "military coup" by Abbas, has effectively split the Palestinians into two geographically divided and separately ruled entities in Gaza and the West Bank.

With Gaza sealed off from the outside world by Israel, there are fears of a humanitarian crisis in the impoverished strip of land although life was gradually returning to normal, with market stalls open and cars about.

Looters had taken to the streets, seizing everything from computers to flowerpots and kitchen sinks from the fallen security strongholds of Abbas's Fatah party and his bullet-scarred presidential compound on the Mediterranean seafront.

On Saturday, gunment from Hamas's armed wing were going house to house in search of Fatah rivals to seize their weapons. At least 200 Fatah men have already fled the territory, by land or sea to neighbouring Egypt.

"Members of the Ezzedine al-Qassam Brigades took my weapons under threat," Ussama, an officer in the pro-Fatah police force, told AFP.

The capture of Gaza by the Iranian- and Syrian-backed Hamas has set off alarm bells in the Jewish state and the international community, further dashing prospects for peace in the Middle East.

Hamas supremo Khaled Meshaal said his Islamic Resistance Movement was not however seeking to take power in the territories and vowed to cooperate with Abbas.

"No one questions his legitimacy. He is an elected president. We are going to cooperate with him in the national interest," Meshaal said at a Damascus press conference.

The US State Department declared its full support for the Abbas-declared government and hinted of stepped up security aid amid fears of alleged destabilisation activities by Iran and Syria.

Washington has watched helplessly as moderate Middle East regimes from Baghdad to Beirut, and now Gaza, have been dragged into cycles of bloodshed, while its arch-foes in Tehran and Damascus strengthen their grip in the region.

Hamas, which swept to victory in 2006 polls but is branded a terror outfit by Israel and the West, overran Gaza after Abbas sacked the unity government and declared a state of emergency in a bid to avert all-out civil war.

A senior Israeli official told AFP it was willing to normalise ties with the Palestinians if the new government recognises the Jewish state's right to exist, renounces violence and abides by past agreements.

But Hamas's sacked premier Ismail Haniya has vowed to carry on in government.

Meeting at crisis talks in Cairo, Arab foreign ministers urged both Hamas and Abbas to step back from the brink, condemning the "criminal acts" in the Gaza Strip.

They stressed "the need to respect the legitimacy of the Palestinian nation headed by Mahmud Abbas and respect elected institutions, including the Legislative Council," where Hamas has a majority.

The White House voiced its backing for the embattled Abbas and said it will not turn its back on Palestinians who oppose Hamas.

"No one wants to abandon the hundreds of thousands, if not millions of people in the Gaza Strip to the mercies of a terrorist organisation," spokesman Scott Stanzel said.

State Department spokesman Sean McCormack said the Middle East quartet had already started looking into plans to help the new Palestinian government, implying the aid boycott would be soon lifted.

Israel, whose Prime Minister Ehud Olmert is heading to Washington on Sunday for talks with President George W. Bush, would also be ready to release some 600 million dollars in badly-needed Palestinian tax money it had withheld since Hamas rose to power.

The Quartet also expressed its full support for Abbas but was "deeply concerned about the humanitarian situation" in the Gaza Strip, according to EU foreign policy chief Javier Solana's spokeswoman.

About 1.5 million Palestinians live in mostly dire poverty in Gaza, one of the most densely populated places on the planet.

The International Committee of the Red Cross put the number of dead over the past week's fighting at 116, with more than 550 wounded, and warned that medical facilities were unable to cope.