According to a survey by the RSM business-advisory group, the vast majority of business executives in Europe want Britain to stay in the EU, while three-quarters say an exit would hurt the UK economy.

Adrian Tripp, chief executive of the European Business Awards programme (sponsored by RSM), said: “There are different opinions in different countries, but the overall opinion of the European business community is that leaving the EU would be really bad for the UK — and for the EU.” Of 437 business leaders surveyed in 32 countries, 76% said a British exit would hurt the UK economy, while 56% said it would damage their own business.

The Conservative Party has promised a referendum on EU membership by 2017, while the UK Independence Party has said that it wants one before Christmas. Labour, the Scottish Nationalists and the Liberal Democrats back continued EU membership without a referendum.

Simon Walker, director general of the Institute of Directors, says only 6% of his members have declared that they would definitely vote for exit in a referendum on the EU, while 60% say that their support for remaining in the EU is contingent on securing adequate reform. Katja Hall, deputy director general of the CBI, said: “It is the clear view of most businesses across the UK that our economic future is best served by our continued membership of a reformed EU.”

Meanwhile, according to a poll by Populus published in The Financial Times last week, UK voters are evenly split on whether they would vote to leave the EU; 39% favoured an exit, while 40% said they would opt to stay in. The support for an exit is much higher among the older generation, who are also more likely to vote in a referendum, the Populus poll said. It found that those aged over 45 are in favour of leaving by 47% to 35%, while those aged 18 to 44 are in favour of staying in by 47% to 29%.

Populus managing director Rick Nye said: “ There is a real divide between those two different age groups. There seems to be more enthusiasm for staying among younger voters.”