BRITAIN will not pay "anything like" the £1.7billion demanded by the European Commission and will challenge it in every way, David Cameron has insisted.

The Prime Minister's defiance came just hours before a new Comres poll showed a rise to a record high in support for Ukip in wake of the Brussels cash-grab.

The snapshot placed Nigel Farage's party on 19 per cent, up four points since last month, and one point above its previous record high in a Comres poll in June.

The Conservatives were up one point to 30 per cent, bringing them equal with Labour, which has slumped by five points to its lowest level under Ed Miliband. The Liberal Democrats, meantime, were down by one point to nine per cent.

Adding more political pressure to Mr Cameron ahead of the November 20 Rochester by-election were suggestions that his aides had privately warned the PM of "not 46 but 70 letters", calling for a vote of confidence in his leadership if he paid the full amount or an insignificantly reduced bill.

In a Commons statement, Mr Cameron told MPs the row over the £1.7bn bill was undermining support for British membership of the EU and warned the Commission that it must change if it was to regain taxpayers' trust.

But Jacek Dominik, the Budget Commissioner, said any attempt by the UK to renegotiate the figure, which reflects changes in the relative national income of different EU states , would risk opening a "Pandora's box", which could threaten the future of the UK's £3bn-a-year EU rebate. Later, No 10 made clear Britain's rebate was not up for grabs.

Mr Dominik suggested it would be "extremely difficult" for the UK to challenge the Brussels demand as any change would require securing the support of a qualified majority of member states for amendments to EU law.

The Commissioner warned the UK was obliged by law to pay by December 1 and would be liable for "late payment fines" if it failed to do so on time.

Yesterday, Mr Cameron looked as though he was fast losing allies in his bid to face down the Eurocrats. Jeroen Dijsselbloem, the Dutch finance minister, indicated the Netherlands would pay their €642m bill "if facts and figures are correct" in the EU's new calculation method while Enda Kenny, the Taoiseach, said that the Irish government would pay its additional bill, noting: "We have always abided by the rules."

In his statement to MPs, the PM said: "Britain will not be paying €2bn to anyone on December 1 and we reject this scale of payment.

"We will be challenging this in every way possible. We want to check on the way the statistics were arrived at, the methodology that was used. We will crawl through this in exhaustive detail," he declared.

He added: "We are not paying two billion on December 1 and we are not paying a sum anything like that. That is very clear."

But Ed Miliband accused the PM of being "asleep at the wheel", claiming he should have been aware for at least two years that changes to Britain's contribution to the EU budget were in the offing.