A Euro MP has quit the front bench in protest at David Cameron's "confused" Lisbon Treaty referendum U-turn.

Roger Helmer said he was resigning as Conservative employment spokesman in Brussels because he could "neither justify nor support" the party's new EU policy.

Mr Helmer was not available to speak to the Leicester Mercury, but wrote his reasons for quitting on the ConservativeHome website.

He wrote: "What we have is an essentially cosmetic policy.

"We are installing a largely ineffective burglar alarm when the family silver has already been stolen.

"But the British people don't want vague promises. They want the family silver back in good order."

The move came less than 24 hours after prominent eurosceptic MEP Daniel Hannan announced on Wednesday night that he would quit to campaign for referendums and other public involvement.

Mr Helmer, MEP for the East Midlands, said there was a "duty" to hold a referendum of some kind on EU policy.

He said he would continue to fight for a Conservative win at the next general election, but added: "I can neither justify nor support our new EU policy.

"In these circumstances, I have concluded that I can no longer continue to serve as a spokesman for the delegation.

"I have accordingly resigned both my spokesmanships with immediate effect."

Mr Cameron promised to try to wrest back powers from the European Union after conceding that the ratification of the Lisbon Treaty made a public vote impossible.

He also vowed to change the law so that no further powers could be lost to the EU without a UK referendum.

The Conservative leader in the European Parliament, Timothy Kirkhope, described the resignations of Mr Helmer and Mr Hannan as "regrettable," but insisted the majority of his MEPs backed Mr Cameron's policy.

"Both Mr Hannan's and Mr Helmer's views on Europe are well known.

"It is therefore no great surprise, however regrettable, that both have decided to resign their positions," he said.

"Mr Cameron's stance on Europe commands my strong support and the strong support of my delegation.

"We will not be diverted from protecting the best interests of the British people whilst at the same time playing a key role in the activities of the EU."

The former leader of Conservative MEPs, Edward McMillan-Scott, has called on Mr Cameron to expel Mr Helmer and Mr Hannan from the party.