The Prime Minister said he had been “misinterpreted” after widespread reports claimed he had ruled out allowing members of the government to follow their conscience on the key issue.
And he insisted he would not answer “hypothetical” questions about what the arrangements would be after he has finished his drive to renegotiate the UK’s membership terms.
Speaking at a press conference yesterday at the end of the G7 summit in Germany, Mr Cameron said: “It is clear to me that what I said yesterday was misinterpreted. I was clearly referring to the process of renegotiation.
“But the point is this. I have always said what I want is an outcome for Britain that keeps us in a reformed EU. But I have also said we don’t know the outcome of these negotiations, which is why I have always said I rule nothing out.
“Therefore it would be wrong to answer hypothetical questions. I know that can be frustrating. I know you want to jump to the end of the process and have all the questions answered now about the end of that process. That is not going to be possible. You are going to have to take this stage by stage, step by step, and you will get the answers.”
The Prime Minister said he had decided to restate his position after reading the reports of his comments in the press.
“What I said is, 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 that will lead to a successful outcome,” Mr Cameron said.
“That is what I said. I feel that there was a misinterpretation which is why I woke up and read the newspapers and thought, ‘I will repeat what I said and make that very clear’.”
He denied the Tories’ difficulties over Europe were an echo of their 1990s splits. “The Conservative Party is delighted that we have got a renegotiation, reform and referendum agenda. There’s complete unity about that, how the manifesto set that out.”
He added there was “real unity” behind his plan, which was “right for the country”. “In the end that’s what this is about: what is in Britain’s national interest. I believe it’s in our national interest to try and make changes in the European Union, changes in our membership, and then give the final decision to the British people.”
He refused to be drawn on whether a minister could remain in the government if he or she disagreed with that “clear view”.
Former cabinet minister John Redwood said up to 200 Tory MPs, out of 330, could be prepared to join a new Eurosceptic grouping, formed to press for a radical renegotiation of the terms of Britain’s membership.