David Cameron has performed a dramatic U-turn on his "back or sack" ultimatum to his Eurosceptic ministers ahead of a promised referendum on the UK's membership of the EU.

It took just a day for the prime minister to withdraw his threat, after he said: "If you want to be part of the government you have to take the view that we are engaged in an exercise of renegotiation to have a referendum and that will lead to a successful outcome.

"Everyone in government has signed up to the programme set out in the Conservative manifesto."

The Tory leader, who secured a shock majority at the general election, made the comments at the G7 summit in Germany.

Number 10 have now reportedly said that his remarks were "over-interpreted" by the press lobby and that Cameron was referring to ministers' duty to maintain collective responsibility as the negotiations between Westminster and Brussels continue.

The prime minister later made his own statement on the issue, claiming that he was "misinterpreted".

"I was clearly referring to the process of renegotiation and I'm happy to repeat exactly what I said," Cameron added.

David C Bannerman, Tory MEP for Eastern England and former deputy leader of Ukip, told IBTimes UK that Cameron's position is "very reasonable".

"My understanding is that this is not a climb down but a clarification. I understand that they mean cabinet responsibility applies during the renegotiation process, but may be suspended during referendum, which seems very reasonable," the Eurosceptic said.

The move comes after IBTimes UK spoke to another one of the Conservative Party's leading Eurosceptics, John Redwood.

The senior MP warned Eurosceptics that it would be unusual to form a "Brexit" campaign before the government has even secured its first substantial move towards holding a referendum on the UK's membership of the EU.

Redwood explained that he would concentrate his efforts on lobbying the government as a member of the newly formed Conservatives for Britain group.

"We are not an 'Out' campaign, the 'Out' campaign will form in due course. It would be unusual to form an 'Out' campaign before we even have an EU referendum bill put through the House of Commons," he said.

But the Tory said he had "no idea" whether the prime minister could secure a better deal for Britain from the political and economic union. He added: "It depends on how much they want to keep us in, doesn't it?"