But if a new settlement is not accepted by Britons, Cameron promises a referendum after 2015 on whether the country should continue to stay in the EU.

 

　　"It will be an in-out referendum. Legislation will be drafted before the next election. And if a Conservative Government is elected we will introduce the enabling legislation immediately and pass it by the end of that year. And we will complete this negotiation and hold this referendum within the first half of the next parliament. It is time for the British people to have their say. It is time for us to settle this question about Britain and Europe."

 

　　But experts believe the pledge itself could cause problems.

 

　　George Magnus is Senior Economic Adviser to UBS Investment Bank.

 

　　"If the government steers the United Kingdom towards a referendum, and people decide they want to quit, then of course the government has to leave, and that could be very disruptive for the British economy. It could be disruptive for inward investment. It could be disruptive for inflation in the United Kingdom, for the pound sterling. Economically and socially I think it would be really quite a problem."

 

　　Cameron has insisted it's not in Britain's interest to leave the European Union. He also warned that leaving the EU would be a "one-way ticket, not a return". But he's been facing growing pressure from within the Tory party to stage a referendum on the issue.

 

　　"I think the government is wrong to be having this debate. I think it's very much about the internal politics of the Conservative Party. And I hope we'll forget about it quite quickly."

 

　　The opposition Labour Party has said that Cameron's move demonontrates weak leadership. Labour leader Ed Miliband reacted by ruling out a similar referendum if Labour wins the next general election.

 

　　In Europe, Cameron's speech has triggered mixed reactions, with positive responses from Sweden and the Netherlands, and warnings from Germany and France.

 

　　For CRI, I'm Tu Yun reporting from London.