A Conservative Government would not seek to reopen negotiations on the Lisbon Treaty if the controversial document has been ratified by all 27 EU states by the time it comes to power, shadow business secretary Kenneth Clarke said yesterday.
Mr Clarke risked angering Tory eurosceptics by saying he envisaged only "sensible discussions... in limited areas" about the division of responsibilities between Westminster and Brussels.
Tory leader David Cameron has promised a referendum on the treaty - which replaces the failed EU constitution - if he reaches office before ratification is complete.
But he has declined to spell out exactly what he 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 he "would not let matters rest".
Today, Mr Clarke said that this would not mean renegotiation of the treaty - which creates an EU President and removes some national vetoes - but a discussion about the return of competencies to nation states in areas such as employment law.
Mr Clarke secured agreement on his promotion to the shadow cabinet earlier this year that he would not be expected to give up his europhile views, but would not seek to change the party's settled policy on Europe.
His comments today will upset some of the party's eurosceptics, who hope to see the provisions of the Lisbon Treaty rolled back if Mr Cameron wins power.
Mr Clarke told BBC1's The Politics Show: "If the Irish referendum endorses the treaty and ratification comes into effect, then our settled policy is quite clear that the treaty will not be reopened.
"But it has also been said by David Cameron - and he means it - that it will not rest there, and he will want to start discussions on divisions of competence between national states and the centre of the EU.
"He has spelt it out to a certain extent. I think we will want to open negotiations with the EU about a return of some responsibilities, particularly in employment law, to individual nation states.
"These will be sensible negotiations, and I actually don't think that the British will be alone. I think there are some other member states who think it is perfectly legitimate to start considering whether or not something like the opt-out to the old social chapter might not be reconsidered." He added: "I don't think anybody in Europe, including me, is in the mood for any more tedious debates about treaties, which have gone on for far too long, which is why this needs to be resolved.
"We are not talking about a solemn treaty renegotiation. We are talking about sensible discussions about the proper division of responsibilities between nations and the EU in limited areas."