Poll: Almost half of Brits want to leave the EU

It also said 54 percent believe the last 40 years of British EU membership has had a "negative" effect on the country and that 81 percent are happy they do not use the euro.

The numbers are more or less stable compared to December 2010 (the oldest data cited). At the time, 48 percent of people wanted Britain to leave.

Amid talk in the EU of a new banking union and political union, a UK foreign office spokesman told EUobserver that under the EU Act of 2011 a referendum is automatically triggered "if any of these changes result in a transfer of competence from the UK to the EU."

British elections are also a factor.

Ryan Bourne, an analyst at the London-based think tank, the Centre for Policy Studies (CPS), said that when election time comes - whether it is 2015 as planned, or earlier - each party will have to take a clear line on the EU.

He noted the Conservative party might plump for two referendums.

In the first one, it would ask people to vote Yes or No on a list of demands - such as exempting the UK from EU employment, financial, social and trade laws - to take to Brussels.

If British people backed the list, but the EU rejected it, the second referendum would be on whether Britain should get out.

He added that the British public is more eurosceptic than the government.

"A lot of people have the belief that as a sovereign nation, our laws should be determined through our own democratic institutions," he said.

"People realise that in order to get out of the crisis we need growth, but they think some of the laws coming out of Brussels actually kill growth."

The European Commission made light of the Angus Reid results.

Frederic Vincent, a spokesman, said that Brussels will only comment on the prospect of a UK referendum after the British government actually announces one.

For its part, the British foreign office noted that referendum or no referendum, EU-UK relations will be different after the crisis.

"A choice of the status quo or out completely is the wrong question. Europe is changing. We don't know what the EU will end up looking like at the end of this crisis," its spokesman said.