The Tories faced fresh questions over their new European Parliament alliance today after it emerged its Polish chair has backed both the Lisbon Treaty and the Common Agricultural Policy.
Law and Justice Party MEP Michael Kaminski told his Law and Justice Party's website that the treaty "guarantees Poland's sovereignty".
That would appear to put him seriously at odds with David Cameron who is strongly opposed to the treaty which he wants to put to a referendum in the UK.
It is the latest controversy to hit the political marriage of convenience with centre-right MEPs entered by the Tories to meet a pledge by the party leader to split from the mainstream centre-right European People's Party (EPP) grouping.
Mr Kaminski, who chairs the new 55-strong European Conservatives and Reformists Group (ECR), has already been forced to deny holding anti-Semitic and homophobic views.
The Tories conceded that there was a difference in policy over the treaty but said it was not explicitly referred to in any of the 10 founding principles of the grouping.
One of those principles is: "The sovereign integrity of the nation state, opposition to EU federalism and a renewed respect for true subsidiarity."
Eurosceptic Tories would have expected Mr Cameron's creation of the new group, which was designed to satisfy their concerns over EU expansion, to involve opposition to the treaty.
Timothy Kirkhope, Tory leader in the European Parliament, said: "Polish Law and Justice, like all other members of our group, has signed up to a set of common principles under the Prague Declaration. This commits us to fundamental reform and change in the EU.
"This includes the EU showing greater respect for the decisions of national governments and therefore we do not believe it is our place to dictate policies to them in matters such as this."
Europe Minister Glenys Kinnock said the grouping was "coming apart at the seams" and called for the Tories to clarify their position on the future of the treaty.
Mr Cameron has promised a referendum on the treaty - which replaces the failed EU constitution - if he reaches office before ratification is complete.
But the party has declined to spell out exactly what it would do if the treaty has been implemented, as is likely if the Irish vote 'yes' in a re-run referendum this autumn, saying only that it "would not let matters rest".
Baroness Kinnock said: "David Cameron needs to get a grip. The fringe is coming apart at the seams. Cameron and (shadow foreign secretary William) Hague must say where they stand. Do they agree with the leader of their group or do they oppose him and move further from reality?
"Repeating the vague Hague mantra 'matters will not rest ' won't do. They must tell us are they supporting their leader Kaminski or will they go further Beyond the Fringe?"
Nick Clegg, the Liberal Democrat leader, said: "David Cameron and William Hague's European policy is now lurching from dogma to farce.
"Even their own handpicked European allies disagree with them. Cameron and Hague have become an irrelevant laughing stock in Brussels."
The Observer said Mr Kaminski, in an interview with his party's website, also declared that: "We must be allied with those EU countries that defend the Cap."
Europe's agricultural policy is criticised in the UK by both eurosceptics and strong supporters of the EU, such as Labour former Europe minister Denis MacShane.
"It now turns out that Michal Kaminski who is leader of the Tory MEPs in their new group in Strasbourg is a strong advocate of the EU's most corrupt, wasteful spending programme," he said.
"What is David Cameron doing in alliance with this man? Critics of the Cap like the Yorkshire Tory MEP Edward Macmillan Scott have been expelled from the Conservatives to appease this Cap junkie from Poland."