The rise of the UK Independence party has coincided with increased support for Britain remaining part of the EU, according to a survey published on Wednesday (22 October).

Fifty-six percent of Britons would vote to stay in the 28-country bloc, the highest level since 1991, the survey by pollsters Ipsos Mori found. Thirty-six percent said they would vote to leave, while 8 percent were undecided.

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The data marks a big shift since the depths of the eurozone crisis in 2011 and 2012 when a narrow majority of Britons favoured leaving the EU.

More than three out of every four Labour and Liberal Democrat voters back EU membership, along with one in two Conservatives.

“There is a polarisation in views," said Ipsos Mori's head of research Gideon Skinner. "UKIP supporters are twice as likely to say Europe is going to be important to their vote in the next election and are much more sceptical, while supporters of the other parties put the issue lower down on their list and are more in favour of membership,” he added.

Meanwhile, 43 percent of the 100 respondents wanted Britain's relationship with the EU to remain unchanged or involve more integration, while one in three called for Britain to revert to purely economic relations with the other 27 countries in the bloc.

According to Ipsos Mori's data, previous peaks in public support for EU membership amongst Britons were in the early 1980s and then between 1989 and 1992, when Britain was part of the Exchange Rate Mechanism (ERM), the forerunner to the euro.

The recent surge in support for Nigel Farage's UK Independence party, just over six months ahead of next May's general election, has sent both the Conservative and Labour parties into panic.

Having topped the poll at the European Parliament elections in May, UKIP won its first MP in the House of Commons on a 50 percent swing at the Clacton by-election earlier this month, and is widely tipped to win a second MP in November. The by-elections were caused by Conservative MPs Douglas Carswell and Mark Reckless defecting to UKIP and prompting snap polls.

Fearful of further defections so close to next May's general election, David Cameron is under increasing pressure from his Conservative party to proposed a cap on EU migration.

Cameron is expected to set out his proposal on reforming EU migration controls before Christmas, Westminster sources said.

Labour, too, has vowed to re-examine the EU's rules on freedom of movement in a bid to assuage public fears about so-called 'welfare tourism', whereby migrants access the UK's social benefits system and free health service.