Nigel Farage says some top Tories only support EU membership to help their careers

Cabinet ministers will be officially allowed to campaign either way

Ukip will 'lead the charge' for an Out vote, Farage will say (Getty Images)

Some Conservative Cabinet ministers who will campaign to stay in the European Union are putting their “careers before their conscience”, Nigel Farage has said.

The Ukip leader said he wasn’t sure which top Tories would join the “Out” campaign but hinted that he believed that privately many were against EU membership.

“There’s been lots of speculation about will Boris Johnson back the Out campaign? Will Theresa May back the Out campaign?” Mr Farage told the BBC Sunday Politics programme.

“What I suspect is most senior politicians in the Conservative party will put their careers before their conscience and back the Prime Minister’s position.”

He said he did not believe this would matter because the referendum would be “the people versus the politicians”.

Mr Farage’s comments come as Nick Herbert, a Conservative minister thought of as a eurosceptic, said he would campaign to remain in the European Union.

Former chancellor Lord Lawson, who leads a eurosceptic group, however told the Financial Times yesterday that a Conservative Cabinet minister would lead the “Out” campaign.

Chris Grayling was the first Conservative Cabinet minister to announce he was prepared to campaign to leave the European Union, having announced last week that staying in the bloc would be “disastrous”.

“I am someone who believes that simply staying in the EU with our current terms of membership unchanged would be disastrous for Britain,” he wrote in an article for the Daily Telegraph newspaper.

“That's why I have always believed that it is imperative that his renegotiation takes place and delivers as much potential change as possible. It is in the interests of all eurosceptics and of our country.”

Downing Street said it was relaxed about Mr Grayling’s statement.

There has been speculation that more senior figures could back the campaign to leave after Mr Cameron said frontbenchers would be free to campaign either way.

The Conservative party harbours different about whether Britain should remain in the European Union.

Mr Cameron’s position is to hold an in-out EU referendum after renegotiating the bloc’s terms of membership for Britain.

His renegotiations so far have focused on restrictions to in-work benefits paid to EU migrants