The U.S. strengthened its offer of support for President Mahmoud Abbas on Saturday, telling him an international aid embargo against the Palestinians would end as soon as he forms a new government without Hamas, aides to Abbas said.

The United States and European Union have backed Abbas in light of the upheaval that has remade the Palestinian territories. Jacob Walles, the American consul-general in Jerusalem, said Saturday he expects Washington to lift the 15-month economic embargo.

"I expect that we are going to be engaged with this government," Walles said. "I expect that early next week. There will be some announcements in Washington, specifically about our assistance and about the financial regulations."

The Hamas-controlled Gaza Strip and the Fatah-controlled West Bank have effectively become separate political entities, endangering the Palestinian dream of forming an independent state in the two territories.

Hundreds of Fatah gunmen stormed Hamas-controlled institutions across the West Bank on Saturday, seeking revenge for the Islamic group's violent takeover of the Gaza Strip.

Crowds of Gaza Strip residents converged on the border crossing with Israel desperate to leave the coastal strip, but they found locked gates. Israel, meanwhile, said it would allow food and other basic supplies into Gaza.

In Gaza, the deposed prime minister appointed a new security command to solidify control. Despite Hamas pledges to restore calm, looters attacked several prominent Fatah symbols, including the home of longtime Palestinian leader Yasser Arafat.

In the West Bank, Abbas' newly appointed Palestinian prime minister, Salam Fayyad, moved forward with plans to form an emergency government. Officials close to Abbas said the government would also include members from Gaza, underscoring Abbas' claim to lead all Palestinians. Hamas, which now claims its own government in Gaza, called the move illegal.

Abbas aide Yasser Abed Rabbo said the new government would be sworn in by Sunday. He also rejected negotiations with Hamas: "There will be no dialogue with killers who carried out field executions in Gaza."

Aides to Abbas said Walles pledged an end to the sanctions once the new Palestinian government is formed, aides to Abbas said, speaking on condition of anonymity because the meeting was closed.

The sanctions were imposed after Hamas, which the U.S. has branded a terrorist group, was elected in January 2006. Hamas and Fatah have been locked in a power struggle since then, especially over which group would control security forces.

A Western diplomat, speaking on condition of anonymity, said all restrictions will be lifted, including those on bank transfers. The EU's statement said the question would be discussed at a meeting of the bloc's foreign ministers in Luxembourg.

In Washington, State Department spokesman Sean McCormack described Fayyad, Abbas' new prime minister, as "a person that the international community has long experience with, has great confidence in."

In Gaza, deposed Prime Minister Ismail Haniyeh who has ignored Abbas order firing him replaced security commanders loyal to Abbas, a spokesman aid.

Since seizing control of Gaza on Thursday, Hamas has tried to impose law and order in the area, in part due to fears of retribution in the West Bank. Saturday's attacks on Hamas targets were the most serious so far.

In Ramallah and Nablus, hundreds of Fatah gunmen took over the Palestinian parliament and other Hamas-controlled government offices, and said staffers with ties to Hamas could not return.

At the parliament, several hundred Fatah supporters chanted, "Hamas out," while gunmen climbed on the roof of the building and fired in the air. They also whisked the deputy speaker, a Hamas ally, out of the building, but were prevented from pushing him into a car.

Many government employees tied to Hamas, apparently fearing they would come to harm, never came to work Saturday, the start of the work week in the West Bank.

In Gaza, meanwhile, Hamas forces on Saturday blew up the home of a prominent Fatah family, collected rivals' weapons and deployed hundreds of security men at strategic locations.

"They are going to provide the people with all the security they have lacked in the past few years due to the bad behavior of some corrupt agents," said Abu Hilal, the Hamas spokesman.

With Hamas firmly in control, Gaza City's streets largely returned to normal Saturday. Outdoor markets were alive, and traffic jams clogged the streets a dramatic contrast to the street battles seen earlier in the week. Still, jittery residents stocked up on flour and other basic supplies in fear of further violence.

Hamas units took up positions at former Fatah security buildings. At the damaged headquarters of the Preventive Security Agency, Hamas said it found the bodies of seven people it claimed were executed by the pro-Fatah force before it was routed.

Despite Hamas' pledges of calm, looting persisted at key Fatah symbols, including the home of Arafat, the founder of Fatah who ruled the Palestinians for 40 years.

Witnesses said gunmen stormed the house early Saturday, taking furniture, including a bed, and three cars. Hamas security forces later arrived and locked the house. The home had been empty since Arafat left Gaza in 2001. He died in 2004. The witnesses declined to be identified, fearing for their safety.

Despite Hamas promises of amnesty, fearful Fatah supporters converged on the Erez border crossing with Israel in hopes of traveling to the West Bank. One young man shouted "bye, bye, Gaza," and waved as he walked through the covered walkway that leads to the Israeli side.

Israeli government spokesman Shlomo Dror said only a small number of "humanitarian cases" were allowed to pass. At the same time, hundreds of people looted police positions on the Palestinian side of Erez, and at one point Israeli troops fired in the air to keep the crowd at bay. The looters walked off with furniture and scrap metal.