"I've set out a positive case to say that we are safer, stronger and better off if we stay."

On his benefit reforms, he said: "For years people have been complaining about something for nothing. This ends something for nothing."

He added that it was "positive" and "a very good move" to encourage migrants to come to Britain and pay in before they take out.

On his promised exemption from "ever closer union", he said: "People talk about the risks of staying. I don't believe there are any risks to staying. If there are any future changes, by law there must be a referendum on those."

On immigration he said: "We don't solve our immigration issues by leaving the European Union but we do create massive problems for our economy.

"We are reopening the freedom of movement directive because of the renegotiation. This is now an ongoing process. If we stay in the negotiations will continue."

Asked how he will pull the country back together if the result is close, he said: "I think by accepting the result of the British publish and bringing the Government back together to focus on the issues we really want to focus on."

He insisted that by remaining in the EU "we are not shackled to a corpse", adding that "the vision of Britain in Europe is that we have a special status. We have the best of both worlds."

Mr Cameron said: "We are proud Brits and proud of what we can achieve, but frankly we can achieve more if we are in these organisations fighting for what we want. Britain doesn't quit."