JERUSALEM - Palestinian officials said Sunday they are preparing to ask the United Nations to endorse an independent state without Israel's consent because they are losing hope they can achieve their aspirations through peace talks. The announcement drew a harsh rebuke from Israeli officials.

In the West Bank, meanwhile, the Palestinians announced plans to extend the term of President Mahmoud Abbas after a recommendation to postpone presidential elections indefinitely.

Chief Palestinian negotiator Saeb Erekat said frustrated Palestinians had decided to turn to the UN Security Council after 18 years of on-again, off-again negotiations with Israel. The Palestinians seek an independent state that includes the West Bank, Gaza Strip and east Jerusalem -- areas captured by Israel in the 1967 Mideast war.

"Now is our defining moment. We went into this peace process in order to achieve a two-state solution," he said. "The endgame is to tell the Israelis that now the international community has recognized the two-state solution on the '67 borders."

U.S. efforts to restart Israeli-Palestinian peace talks are deadlocked. Israeli Prime Minister Benjamin Netanyahu has urged the Palestinians to negotiate with him. But they refuse, saying Netanyahu must first stop building settlements on lands they claim. Netanyahu refuses to endorse the 1967 lines as the basis for an agreement.

Even if the UN endorses the Palestinian idea, it would be virtually impossible to implement while Israel remains in control of the West Bank and east Jerusalem. Nearly 500,000 Israeli settlers live in these areas, in addition to thousands of Israeli troops stationed on bases.

The Palestinians already declared independence unilaterally on Nov. 15, 1988. The declaration was recognized by dozens of countries, but never implemented on the ground.

In the meantime, the Palestinian prime minister, Salam Fayyad, has begun a two-year development plan meant to lay the groundwork for independence.

Speaking in the West Bank, Fayyad said his development efforts are separate from the independence plan. He said his government's goal is "getting ready for statehood," while the Palestine Liberation Organization would decide when to declare independence.

Fayyad spoke at a news conference with U.S. Senator Joseph Lieberman, who praised Fayyad's efforts to develop the economy.

"I know some people are concerned that this is unilateral," he said, referring to his development plan. "But it seems to me that it is unilateral in a healthy sense of self-development." He did not comment on the independence plan.

Erekat declined to say when the Palestinians would make their appeal to the UN, signalling that the threat may be aimed in large part at putting pressure on Israel.

Israeli Defence Minister Ehud Barak warned that Israel risks watching the international community line up behind the Palestinians if negotiations are not restarted. "Without an agreement, there is a possibility that support will increase for the Palestinians declaring a state unilaterally," he told the Cabinet Sunday.

Israeli Vice Prime Minister Silvan Shalom, a member of Netanyahu's Likud Party, warned the Palestinians against taking any one-sided action. "I think the Palestinians should know that unilateral actions will not lead to the results they hope for," he said.

Nimr Hamad, an adviser to Abbas, said the Palestinians "have no intention of rushing" to the Security Council.

"We are going to have to prepare for this well and to hold political and diplomatic talks. We want the Security Council to discuss this only after we've been given assurances," he told the Israeli daily Maariv. "There is no point in rushing just so that we collide with an American veto."

As one of the five permanent members of the Security Council, the U.S. wields veto power over any resolution. Israeli media predicted that the U.S., Israel's key ally, would veto the move.

Hamad said Abbas would travel to Cairo Wednesday to discuss the plan with Egyptian President Hosni Mubarak.

There was no immediate reaction from Security Council members. But Erekat said Russia, another permanent member of the Security Council, and unspecified European nations are "on board" with the Palestinian plan.

Complicating the matter is the status of the Gaza Strip. The territory is currently ruled by Abbas' rivals, the Islamic militant Hamas group. Israel withdrew unilaterally from Gaza in 2005.

Last week, Palestinian election officials postponed a planned Jan. 24 presidential election, saying Hamas' opposition made it impossible to hold the vote in Gaza. The decision cleared the way for Abbas, who had threatened to quit politics after the election, to remain in office.

Mohammed Dahlan, a top official in Abbas' Fatah Party, said Sunday that the PLO's central committee will meet next month to extend Abbas' term until elections can be held.