The Quartet issued a statement yesterday taking "positive note" of Sharon's proposal, which calls for a full withdrawal from Gaza but only parts of the West Bank.
UN Secretary-General Kofi Annan, reading the statement, cited a "rare moment of opportunity" for the peace process.
"This initiative, which must lead to a full Israeli withdrawal and complete end of occupation in Gaza, can be a step towards achieving the two-state vision; and could restart progress on the road map," Annan said.
The statement followed a meeting of Quartet members, including Annan, U.S. Secretary of State Colin Powell, Russian Foreign Minister Sergei Lavrov, EU foreign-policy chief Javier Solana, and Brian Cowan, foreign minister of Ireland, which currently holds the rotating EU Presidency.
The Quartet was seeking to revive the initial blueprint for simultaneous steps toward a peace settlement -- known as the road map -- after a period of escalating violence. Arabs had also become angered over U.S. acceptance of Sharon's plan. Some see it as a ploy aimed at retaining large sections of the West Bank.
In accepting Sharon's plan in April, U.S. President George W. Bush raised alarm among Arabs by stating that Israel could not be expected to give up all occupied land or accept a return of Palestinian refugees to what is now the Jewish state. Palestinians saw this as bargaining on issues that they should have been allowed to negotiate with Israel.
But yesterday's Quartet statement said the most sensitive issues must be negotiated by the two sides.
Powell told a news conference that Bush has maintained that all issues in the end will need to be resolved between the two parties.
"We did not prejudge,” Powell said. “We made a statement about what we believe is appropriate, what might have to happen in order to get to final settlement. But ultimately, final settlement is something to be resolved between the two parties themselves in negotiation with each other with the assistance of the international community in a manner consistent with the road map."
Powell said he hoped the Quartet's statement would provide assurances to the Arab world about the U.S. commitment to the road map. At the same time, he said, the region should seize the opportunity to move beyond the current stalemate.
"Where were we going with this process? Where were we a few weeks ago? We were still hoping for something to break, something to come into the equation that would change the equation and give us something to work with. We now have that with the stated intention of Prime Minister Sharon and the clear support of the Israeli people to move in this direction. And this gives us something to work with and we're trying to take advantage of that opportunity," Powell said.
Powell was citing Israeli polls which show a majority of citizens favor a pullout from Gaza. But a majority of members of Sharon's own Likud party voted on 2 May to reject the plan. Sharon is now considering possible amendments to it.
Solana, the EU foreign-policy chief, said the Quartet statement recognizes the Sharon plan as a means to reaching the goal of ending the occupation of land Israel seized in the 1967 war.
"We said very clearly that that withdrawal has to be total, it has to be the end of the occupation in that territory. I think it's a very important document. The one we have achieved here today among the Quartet can put the Quartet again at the center of gravity of the peace process," Solana said.
The Quartet statement also spelled out the need for reform of Palestinian governing structures. It said Palestinian security services should be restructured to provide law and order for Palestinians, end terror attacks against Israelis, and dismantle terrorist capabilities.
It said Quartet members were ready to intensify their engagement with the Palestinians and improve their living conditions. It expressed the need for an "empowered" Palestinian prime minister and cabinet to help reinvigorate the reform agenda.
Annan told the news conference that Quartet members would need to supervise such reforms.
"We are prepared to engage with a responsible and accountable Palestinian leadership, committed to reform and security performance," Annan said. "The Quartet members will undertake to oversee and monitor progress on these fronts."
The Quartet statement also called on the Israeli government to take no steps that would undermine trust, such as destruction of Palestinian homes and infrastructure or deportations. It urged Israel to take immediate steps to ease humanitarian conditions for Palestinians, including freedom of movement for people both within and from the West Bank and Gaza.