Cameron faces new referendum revolt

In a move seen as an attempt to appease the critics in his own party, Mr Cameron's office revealed that he had written to the president of the Czech Republic to restate his opposition to the treaty.

But that admission came just hours after Mr Cameron had insisted he did not want to make a firm commitment to holding a referendum on the treaty in the UK for fear of prejudicing the decision yet to be taken in the Czech Republic and Poland.

Mr Cameron's stance was further undermined when Tory MEP Daniel Hannan, an arch Eurosceptic, insisted that his party leader was "working privately to get a referendum on the Lisbon Treaty".

Ireland's decisive backing of the treaty on Friday paved the way for it to be adopted across Europe, which only remains to be ratified by Poland and the Czech Republic.

Tory divisions over Europe spilled into the open yesterday as activists began to gather in Manchester for the last party conference before the general election.

The Lisbon Treaty, born out of the rejected European Constitution, was billed as a document of reform to streamline decision-making in Brussels. It will create a president of Europe and an EU foreign minister, reduce a state's ability to veto and increase powers for the European Commission.

Eurosceptics are pushing for a referendum on the treaty to be held in the UK even if the treaty has been fully ratified by the time the Tories come to power, while pro-Europeans in the party warn that such a move would be would be "ludicrous".

Mr Cameron is under intense pressure from the Eurosceptics in his party, many of whom backed him for the leadership on the condition that he pulled the Tories out of the centre-right EPP group in the European Parliament – a vow he has fulfilled.

Expectations have risen that Mr Cameron will adopt a more hardline approach on Europe after linking up with a more right-wing alliance in Brussels.

London Mayor Boris Johnson – who has not ruled out standing as Tory leader in a future contest – said Mr Cameron should hold a referendum whether or not the treaty had been ratified.

In an article in a Sunday newspaper, Mr Johnson said British voters would be "jealous" of the Irish if they were denied a vote.

"I do think it would be right for such a debate to be held, particularly if the upshot of the Lisbon Treaty is going to produce President Blair," Mr Johnson said, referring to the widely held belief that former prime minister Tony Blair is the favourite to become the first president of the European Union.

Eurosceptic veteran Tory backbencher Richard Shepherd said the party must go ahead with a referendum regardless of whether the treaty was already in force.

"We were committed to it and I believe that this is a matter of the deepest trust with the British people that we will honour that which we gave the commitment for," he said.

Conservative Party chairman Eric Pickles waded into the row by predicting that the Czechs and Poles would not have sorted out their positions by the time of a UK general election.

He said: "We know from the Czech Republic that they are going to take between three and six months, we have yet to hear from Poland, so the likelihood is that we (in the UK] will have a general election within seven months and we will be able to name the day of the referendum during the election campaign."

But pro-Europeans in the party warned such a move could damage or sever the UK's membership of the EU. Sir Leon Brittan, the former Tory home secretary and UK commissioner in Brussels, said it would be "ludicrous" to hold a referendum when all 27 member states had ratified the treaty. "You cannot expect the others to untangle the whole treaty. It would be a great error for a new British government to get into this position," he said.

Despite the pressure from Eurosceptics, the Tory leader refused to commit to a retrospective referendum.

Mr Cameron said: "I don't want to say anything or do anything now that would undermine or prejudice what is happening in other countries where they are still debating whether to ratify this treaty.

"I think people will understand this argument that, while there are other countries actually delaying the implementation of this treaty, don't do anything or say anything that stops them from doing that."

However, just hours later, his aides admitted that, in a letter to Czech president Vaclav Klaus before the Irish vote, Mr Cameron had restated his opposition to the Lisbon Treaty.

The vexed issue of the EU Treaty threatens to dominate the conference for Mr Cameron, who has enjoyed high poll ratings at the expense of embattled Prime Minister Gordon Brown.

More than two-thirds of Irish voters backed the referendum, with only Poland and the Czech Republic apart from Britain waiting to vote for it.

The Eurosceptic Bruges Group also had a warning for the Tory leader. The group said: "(David Cameron] must show leadership and announce that a retrospective referendum will be held in Britain. This will rule the Lisbon Treaty null and void in the UK and withdraw us from its provisions."