Of those that are worried about its impact, almost half (46%) are worried that it will cause uncertainty among inward investors, over a quarter claim it will cause them to delay on investment decisions for their business and a further 23% are concerned that it could raise doubts about their foreign customers continuing to work with them.

The findings come from the latest Close Brothers Business Barometer, a quarterly survey that canvasses the opinion of SME owners and senior management across the UK.

David Thomson CEO of Close Brothers Invoice Finance said: “It appears that UK firms are split over the prospect of an EU referendum.

“It is understandable that some firms are feeling anxious about the prospect, however, it is important to keep in mind that this potential referendum is still more than two years away and in the meantime we must continue to focus on encouraging investment and paving the way for growth so that we can continue to create stability and security.

“There is evidence that there has been significant foreign investment flowing in to the UK as a direct result of our EU membership*. Last year, the UK’s foreign direct investment stock was greater than any of our European neighbours.”

Thomson added: “The UKIT inward investment report showed record levels of job creation with 66,390 new jobs last year, the highest since 2001. In total 1,773 investment projects were set up by foreign businesses during the 2013 to 2014 financial year.

“These figures are significant and indeed, we hope that that the prospect of a referendum will not derail the progress we have made in recent years.”

*Source: Grant Thornton, 2013