Abbas painted a cautious and at times bleak outlook for Middle East peace efforts during a visit to the United Nations, where he also held talks with Israeli President Shimon Peres.
Speaking at the Security Council, Abbas and other Arab leaders denounced Israeli settlement expansion, saying it was jeopardizing talks relaunched last November at a conference in Annapolis, Maryland, hosted by U.S. President George W. Bush.
"Settlement activity is not only an obstacle but it risks undermining the peace process," Abbas said a day after he met Bush at the White House to try to keep negotiations alive.
Israel's U.N. envoy, Gabriela Shalev, accused Arab delegations of using the issue to "bash" Israel unfairly, saying they were dodging their responsibility to condemn Hamas, which advocates the destruction of the Jewish state.
There is increasingly widespread doubt about meeting Bush's target of a peace deal, including agreement on creation of a Palestinian state, before he leaves office in January.
Despite that, U.S. Secretary of State Condoleezza Rice told Reuters "I think it's possible" to reach an accord this year.
Talks have been complicated by political instability in Israel. Olmert resigned this week in the face of corruption allegations and is staying on in a caretaker capacity while Foreign Minister Tzipi Livni tries to form a new coalition.
"I will pursue negotiations with Mr. Olmert and I will never cease to negotiate even with his successor," Abbas said.
‘Serious Threat’
But Abbas said that unless Israel halts expansion of settlements in the occupied West Bank, "It would be futile to dream of the peace that we all hope for. Because if we fail, if we do not attain peace, then the alternative poses a serious threat. And everyone knows what the alternative is."
"The alternative will plunge the entire region into the deadly cycle of violence once again. I don't even wish to imagine what that might lead us to," he added.
Abbas, a pro-Western moderate who governs only in the West Bank while Hamas Islamists control the Gaza Strip, later told the General Assembly:
"We will continue to strive for the achievement of the maximum progress possible in the current negotiations between us and Israel through the end of this year."
But he stopped short of saying, as he had previously, he hoped to reach a deal with Israel by year-end. Peres told the assembly on Wednesday he now hoped for a deal next year.
"Israel is prepared, if the conditions are ripe, to make painful concessions in the pursuit of peace," Shalev said.
Symbolic of that view, she said, was Peres's meeting with Abbas shortly before the Council meeting, which was called at the behest of Arab countries to air grievances against Israel.
Arab League Secretary-General Amr Moussa said Israeli-Palestinian talks were "futile because there isn't any progress and no Israeli suggestions in the face of the many initiatives presented by the Arab side."
Shalev denied the settlements were "an obstacle to peace." Israel has insisted it has the right to build in large enclaves it intends to keep under any future peace deal.
Talks between the sides have yielded little amid flareups in and around Gaza, including cross-border Hamas rocket fire that has sparked Israeli military action. Israel criticizes the Palestinian leadership for failing to rein in militants.
Addressing the Council, Rice, who has criticized Israeli settlement growth, said the Palestinians as well as Israel have yet to fulfill all their obligations under a peace "road map."
