A business lobby group in the UK has recommended that Prime Minister David Cameron hold a planned referendum on Britain’s EU membership as soon as possible or risk what it called “accidental brexit.”

IoD Director General Simon Walker said:"Britain voting to leave the European Union is at least a 50-50 possibility."

"My concern is the timing of the referendum. I hope this government will not drag out the referendum process any longer than necessary," he added.

Walker also warned that a 2017 vote would see Britain's re-negotiations caught up among French and German elections slated for that year.

Polls show the gap between Britons who want to remain in the EU and those who want to leave remains tight.

Cameron has promised to reform Britain's EU ties and then hold a referendum on whether to remain a member, by the end of 2017.