The United States and other world powers called for the Palestinians and Israel to resume direct peace talks within a month and commit to seeking a deal by the end of 2012.
The Quartet of the United States, Russia, the European Union and the United Nations acted after Palestinian president Mahmud Abbas formally submitted his request to the United Nations for Palestine to be admitted as a full member.
The United States has vowed to veto the unilateral bid at the UN Security Council, arguing that the resumption of direct negotiations between Israel and the Palestinians is the only real path to peace and statehood.
US-brokered talks stalled a year ago when Israel failed to renew a partial freeze on settlement construction in the occupied West Bank, but the Quartet urged both sides Friday to resume negotiations and plotted out a path forward.
"We urge both parties to take advantage of this opportunity to get back to talks," US Secretary of State Hillary Clinton told reporters after talks with her Quartet partners on the sidelines of the UN General Assembly.
A senior Israeli official told AFP on condition of anonymity that his side was "currently studying the statement. We are ready to resume the negotiations."
Palestinian negotiator Saeb Erakat meanwhile urged Israel to "seize" the Quartet offer, telling AFP the Palestinians were "ready to assume our responsibilities" based on a previous Quartet blueprint and international law.
"But Israel needs to assume its own and end settlement activity" in the occupied West Bank, he added.
Urging both sides only to "refrain from provocative actions," the Quartet statement did not explicitly call for a halt to Israeli settlements, which the Palestinians have set as a condition for resuming talks.
Nor did it clearly call for a Palestinian state based on the boundaries that existed before the 1967 war -- which would fulfill the Palestinian desire for a state in the West Bank, the Gaza Strip with east Jerusalem as its capital.
However, it reaffirmed the Quartet's support for US President Barack Obama's "vision" of peace, which called for a deal along the pre-1967 boundaries, albeit with land swaps to allow for Israel to keep some settlements.
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The statement set down a broad timetable for negotiations.
"Within a month there will be a preparatory meeting between the parties to agree an agenda and method of proceeding in the negotiation," it said.
"At that meeting there will be a commitment by both sides that the objective of any negotiation is to reach an agreement within a timeframe agreed to by the parties but not longer than the end of 2012."
Israelis and Palestinians must then produce "comprehensive proposals within three months on territory and security," and they should achieve "substantial progress" within six months, it said.
The Quartet will convene an international conference in Moscow, "at an appropriate time," aimed at giving a boost to tackling those final status issues.
Israeli Prime Minister Benjamin Netanyahu has been discussing Israeli security arrangements for the West Bank with US administration officials, a source close to the talks said.
The four powers also set forth plans for an international donors conference to provide "full and sustained support to the Palestinian Authority" to help it build the institutions for a state.
The statement by the Quartet, whose envoys met intensively all week, emerged following talks involving Clinton, EU foreign policy chief Catherine Ashton, Russian Foreign Minister Sergei Lavrov, and UN Secretary General Ban Ki-moon.
Quartet representative Tony Blair, who has also been involved in the talks, said the proposal was "the only way in the end we deal with the difficulties around the table and in negotiations."
Announcing the Quartet statement, Ashton said "if ever there was a time to resolve this conflict it is now."
"It is now because Israel worries about its security, because the people of Palestine have waited long for their country," she told reporters.
In Berlin, German Chancellor Angela Merkel's spokesman Steffen Seibert said: "The first stone (has been laid) for new negotiations."
A French Foreign Ministry statement said the Quartet action "is a step in the right direction, which is a restarting of negotiations between Israel and the Palestinians."