France’s minister for European affairs, Pierre Lellouche, has warned that the Conservative Party’s stance on the European Union risked marginalising Britain in the 27-member bloc, in a scathing attack on the Tories’ policy towards Brussels.

"It's pathetic. It's just very sad to see Britain, so important in Europe, just cutting itself out from the rest and disappearing from the radar map," Lellouche told British newspaper the Guardian on Wednesday.

The French minister’s comments came just hours after Tory leader David Cameron vowed to repatriate powers transferred to the EU under the terms of the Lisbon reform treaty, a plan Lellouche said would not succeed “for a minute”.

“Nobody is going to indulge in rewriting (treaties for) many, many years," the French minister said, pointing out that any changes would require the agreement of all 27 EU members.

Halting the EU’s ‘steady intrusion’

Cameron, who is widely tipped to become the next British prime minister, said Wednesday he would seek to stop the "steady and unaccountable intrusion" of the European Union into British law.

His speech was intended to reassure the party’s eurosceptics, some of whom have accused him of backtracking on a pledge to hold a referendum on the Lisbon Treaty if he became prime minister.

Instead, Cameron pledged to negotiate the return of powers from Brussels to London if he wins the next general election, and vowed to change British law so that any other treaties would be subject to a referendum.

Disreputable allies

Cameron's speech follows his decision to pull the Conservative Party out of the main centre-right grouping in the European Parliament and join a new rightwing bloc instead, a move that sparked concern among many in Europe.

Britain’s foreign affairs secretary, David Miliband, has seized on the issue as part of the ruling Labour Party’s increasingly desperate election fight-back.

Miliband has repeatedly attacked the Tories for throwing their lot in with the European Conservatives and Reformists group (ECR), which includes controversial Polish, Latvian and Lithuanian parties regarded by many as harbouring extremist views.

Lellouche appeared to echo Miliband’s views on Wednesday, saying the Conservative Party’s stance in the European Parliament had already “castrated” Britain’s influence in the EU’s main legislative body.