President Mahmud Abbas has promised Palestinians he will seek UN membership before the Security Council next week, amid mounting opposition from Israel and the United States.
With Washington calling the move "counterproductive," Abbas told Palestinians in a televised address on Friday: "It is our legitimate right to demand the full membership of the state of Palestine in the UN."
Europe on Saturday joined the diplomatic tussle, calling for a "constructive solution" on Palestinian statehood and a resumption of negotiations with Israel.
"We continue to believe that a constructive solution that can gather as much support as possible and allows for the resumption of negotiations is the best and only way to deliver the peace and two state solution the Palestinian people want," said Jaja Cocijanic, spokeswoman for EU foreign policy chief Catherine Ashton.
Yossi Peled, a Likud party minister without portfolio in the government of Prime Minister Benjamin Netanyahu, told public radio on Saturday Israel could not prevent the Palestinian UN recourse.
"Unfortunately, Israel does not have the means to prevent the Palestinians from demanding adhesion of their state to the UN, and it is impossible to stop them," he said.
"But the initiative will no doubt not get through the Security Council, and will leave us room to negotiate," he said, adding that only direct talks will result in the solution of two states for two peoples.
Washington has already threatened to veto the Palestinian bid in the Security Council.
Abbas made his pledge after Israel boosted its military presence in the West Bank ahead of expected Palestinian demonstrations as the UN statehood bid looms on September 23.
Israel's daily Yediot Aharonot said three battalions of reservists -- some 1,500 personnel -- had been mobilised and units already in the occupied territory had been reinforced.
Explaining US opposition to the planned UN bid, State Department deputy spokesman Mark Toner said: "We believe that any gesture, any movement in New York to that end would be counterproductive to what the real focus should be on, which is direct negotiations between the parties.
"And that remains our goal and our priority."
Direct Palestinian peace talks with Israel foundered nearly a year ago over a dispute over Israel's continued construction of Jewish settlements on occupied Palestinian land.
Abbas said he would seek UN membership "to put an end to a historical injustice by attaining liberty and independence, like the other peoples of the earth, in a Palestinian state on the borders of June 4, 1967."
He was referring to the lines that existed before the 1967 Six Day War, including Gaza, the West Bank and east Jerusalem.
Israel says they are indefensible and the borders of a future Palestinian state must be defined in bilateral negotiations.
Washington says the basis for an agreement should be the 1967 borders but with mutually agreed amendments.
Russia said this week it would support the Palestinian bid at the UN while some 127 countries have recognised Palestine as an independent state.
US Secretary of State Hillary Clinton said two American envoys would return to the Middle East on Tuesday for talks with Israel and the Palestinian Authority.
Israeli Prime Minister Benjamin Netanyahu says he will go to the UN to explain Israel's opposition to the Palestinian move.
A statement from his office said: "Peace is not achieved by a unilateral approach to the UN, and not by associating with the Hamas terror organisation."
"Peace will only be attained by direct negotiation with Israel."
Hamas, the Islamist group ruling the Gaza Strip, hit out at Abbas's strategy, to which it is not a party, saying it could weaken the campaign to allow Palestinian refugees back to their former homes and delegitimise armed opposition to Israeli occupation.
It "carries numerous risks and could violate national rights such as the right of return, the right of resistance and self-determination," spokesman Sami Abu Zuhri said.
Canadian Prime Minister Stephen Harper said Ottawa would also oppose the Palestinian bid.
On Thursday, UN Secretary General Ban Ki-moon urged a return to talks and said the peace deadlock was harming the entire Middle East.
"I am asking them to enter into meaningful negotiations and the international community has a duty to create some conditions favourable to this," Ban said.