Hardline Israeli Foreign Minister Avigdor Lieberman warned Wednesday there would be "harsh and grave consequences" if the Palestinians persist with their plan to seek UN membership as a state.
Speaking shortly before a meeting with EU foreign policy chief Catherine Ashton, he did not elaborate on the possible consequences.
In the past he has called for Israel to sever all relations with the administration of Palestinian president Mahmud Abbas should it press on with its UN bid.
"What I can say with the greatest confidence is that from the moment they pass a unilateral decision there will be harsh and grave consequences," Lieberman told an agricultural conference in southern Israel.
"I hope that we shall not come to those harsh and grave consequences, and that common sense will prevail in all decisions taken, in order to allow co-existence and progress with negotiations," he added.
Some hardline Israeli ministers are calling for Israel to annex chunks of the West Bank if the Palestinians go ahead, though Israeli officials say they have not finalised their response to the UN move as the Palestinians have yet to reveal its details.
"We're not saying what we'll do, a lot of our reaction is subject to what the final resolution will say," a foreign ministry official told AFP earlier this week on condition of anonymity.
US lawmakers, meanwhile, warned the Palestinian leadership Wednesday that they could lose hundreds of millions of dollars in aid if they continue to seek Un recognition.
"Should the Palestinians pursue their unilateralist course, the hundreds of millions of dollars in annual assistance that we have given them in recent years, will likely be terminated," the Democrat Howard Berman said.
Experts, however, told the House Foreign Affairs Committee that cutting off US funding, particularly to Palestinian Authority security programs, would benefit extremists and hurt Israel.
Lieberman has accused the Palestinians of planning an "unprecedented bloodbath" after the UN move, although they say they will hold purely peaceful rallies.
Prime Minister Benjamin Netanyahu and Defence Minister Ehud Barak earlier Wednesday met Ashton in Jerusalem.
An EU statement said that Ashton would hold a second meeting with Netanyahu Wednesday evening.
It quoted Ashton as saying her mission was to ensure that the Palestinians' UN bid would ultimately lead to renewed negotiations with Israel.
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"I met this morning with the Prime Minister and will stay longer than I planned, at their request, so that we can talk again this evening in order to try and further that objective," she said.
"I hope that in the coming days what we'll be able to achieve together will be something that enables the negotiations to start," the statement quoted her as saying.
Netanyahu's office did not immediately comment on the talks, while a short statement from the defence ministry said only that Ashton and Barak had discussed "relations with the Palestinians and the situation in the region."
The EU foreign policy chief arrived from Cairo, where she met Abbas and Arab League ministers who have been discussing Palestinian preparations to request UN membership for a state of Palestine.
Abbas is expected next week to present a membership request to UN Secretary General Ban Ki-moon who will pass it on to the 15-member Security Council for examination.
So far, 127 countries have already recognised a Palestinian state based on the lines that existed before the 1967 Six Day War, including Gaza, the West Bank and east Jerusalem.
Israeli daily Haaretz reported this week that the foreign ministry had instructed its envoys to use last weekend's attacks against the Israeli embassy in Cairo as an argument against supporting the Palestinian campaign.
"What we saw in Cairo demonstrates that despite (Abbas) and other senior Palestinians' declarations that they are not planning a violent confrontation, the violence could also come from the street," the paper quoted from what it said was an internal foreign ministry document.
The ministry would not confirm or deny the story.
US State Department spokeswoman Victoria Nuland said on Tuesday that Washington would "leave no stone unturned" in efforts to deflect the Palestinians from the UN path and get them and the Israelis back into negotiations.
Secretary of State Hillary Clinton said she was sending US envoys David Hale and Dennis Ross to hold talks with Netanyahu and Abbas.
Hale is expected to meet Abbas in Ramallah on Wednesday evening. Netanyahu's office declined to comment on his schedule.
Barak's office said he met Ross on Wednesday and the two discussed the Palestinian issue and other regional matters.
On a visit to the Eshkol region, which flanks the Israel-Gaza border, Israeli President Shimon Peres called for a resumption of talks with the Palestinians.
"We must do all we can to ensure the early resumption of direct negotiations with the Palestinians. I know from experience that what seems impossible can become possible," said Peres.