American ambassador to the UN said the US could withdraw funding from the United Nations if its members decide to recognize an independent Palestinian state.

Susan Rice, the American ambassador to the UN

Susan Rice, the American ambassador to the UN, said there was "no greater threat" to US support and funding of the UN than the prospect of Palestinian statehood being endorsed by member states.

Mahmoud Abbas, president of the Palestinian authority, plans to ask the UN general assembly, which comprises all 192 members, to vote on recognition at its annual meeting in New York in September.

The US and Israel are pressing Abbas to drop his plans. Obama has strongly opposed the move, raising the prospect of a veto in the UN Security Council, which is expected to vote on a Palestinian statehood proposal in July.

However, Palestinian officials have spoken of their determination to a circumvent a US veto by deploying a rarely used Cold War mechanism known as "Uniting for Peace" under which a two-thirds majority in the General Assembly can override the Security Council.

Speaking at an event in Washington, Rice said the Obama administration was devoting "extraordinary efforts and energy" to restarting middle-eastern peace talks so that a vote in September could be avoided.

On the prospect of it being approved, she said: "This would be exceedingly politically damaging in our domestic context, as you can well imagine.”

"I cannot frankly think of a greater threat to our ability to maintain financial and political support for the United Nations in Congress than such an outcome".

Although Palestinians believe they are close to securing such a majority, the General Assembly does not have the power to confer UN membership on a new Palestinian state, meaning that a successful vote would represent little more than a symbolic triumph.

Even so, Republicans in the US Congress are promising to react aggressively to any approval of statehood. Two congressmen have already vowed to initiate bills to withdraw UN funding in the House of Representatives.

The US provides almost a quarter of its $2.5 billion annual budget, making a yearly contribution of almost $600 million.

The US is desperate to avoid being put into a position of having to wield its veto. With growing international support for Palestinian statehood, even in Europe, the US is looking increasingly isolated in its support for Israel and a veto would badly damage Obama's credentials in a rapidly changing Middle East.

However, the US president faces a politically damaging backlash from the pro-Israeli lobby and its many supporters in Congress if he does not block a resolution, a move that could also cost all-important Jewish votes in key swing states like Florida during next year's presidential election.

Obama has already angered the Israeli government and its US supporters by calling for a Palestinian state that roughly corresponds to the existing boundaries of the West Bank and Gaza, which Israel occupied after the Six Day war of 1967.

David Cameron

The move was intended to rejuvenate the stalled Middle East peace process.

Palestinian officials, in public at least, say they remain committed to a UN vote as the only realistic way of breaking the deadlock.

Western powers have backed a two-year Palestinian state-building programme that reaches fruition at the end of August. It has already been judged a success by the World Bank and International Monetary Fund, where Palestinian officials say it would be hypocritical for the West to back the state-building exercise but not its "logical outcome".

Britain has indicated it would not join the US in vetoing Palestinian statehood in the Security Council. But David Cameron is also hoping to avert a highly divisive vote in the general assembly.

"The question is whether we can do anything that might deflect the Palestinians from going ahead with this," a British diplomatic source said.