The Palestinian Authority will agree to return to peace negotiations with Israel if only one of two criteria they had previously set as pre-conditions for talks are reached: an immediate halt to all settlement construction or an Israeli declaration that the borders of the Palestinian state will be based on the pre-1967 lines with mutually agreed upon land swaps, a senior aide to PA President Mahmoud Abbas told Army Radio on Wednesday.

"We believe that both the conditions need to exist together, because they are connected to one another," Nimmer Hammad stated. "However, President [Shimon] Peres tried to get Netanyahu to agree to only one condition and he refused," he added.

Hammad called on Peres to inform the Israeli public that Netanyahu, and not Abbas, is responsible for the impasse in the peace process.

Senior US envoys visiting the Middle East this week in an attempt to revive peace talks and avert a Palestinian bid for UN membership will meet with both Netanyahu and Abbas as part of their efforts, Washington announced on Tuesday.

The mission by US Middle East envoy David Hale and senior White House aide Dennis Ross appears to be a last-ditch push to dissuade the Palestinians from seeking to upgrade their UN status this month.

"The only way of getting a lasting solution is through direct negotiations between the parties and the route to that lies in Jerusalem and in Ramallah, not in New York," US Secretary of State Hillary Clinton told reporters on Tuesday.

"Our hope is that we get the parties back into a frame of mind and a process where they will actually begin negotiating again," she added, a goal that critics, analysts and even an administration ally suggested will be hard to achieve.

US Senator John Kerry, the Democratic chairman of the Senate Foreign Relations Committee who is close to the administration, said there was little chance of stopping the Palestinian bid.

"I think the only thing that might change the dynamic now is a major proposal by Israel on the table with respect to the peace process," Kerry told reporters.

The US ambassador to the United Nations, Susan Rice, met about 20 Democratic members of Congress on Capitol Hill on Tuesday to discuss "mutual efforts" to deter the Palestinians from their UN effort, a spokeswoman for House Democratic Whip Steny Hoyer said.

A senior aide to Abbas told Reuters the plan was still to seek full UN membership for a Palestinian state despite the new US mission.

Earlier, the aide, Mohammad Shtayyeh, said the Palestinian leadership would listen to any proposals but suggested the current US push had come too late.

"We are open-minded to any proposal ... but this is not a step to really stop us from going to the United Nations," he said. "If the whole idea of a proposal is to engage peacefully then you don't really bring it in the last five minutes."

Qatar's envoy to the UN, serving as president of the upcoming General Assembly, said Tuesday that no official request to recognize a Palestinian state has yet been received by the world body, Army radio reported.

Nassir Abdulaziz Al-Nasser emphasized that the exact form the request request will take was still being discussed.