Nearly four in 10 firms (39.3 per cent) said a withdrawal would have a negative economic impact, even if followed by a trade agreement – up from 36.7 per cent when the same question was asked in the second quarter of this year.
The proportion that believes this would be beneficial has fallen to 30 per cent, from 35.6 per cent.
Yet a clear majority still want specific powers transferred back to Westminster. Staying in the EU but renegotiating the membership, an outcome that is being targeted by Prime Minister David Cameron, would have a positive impact according to 57.2 per cent of surveyed firms.
The survey was held by the British Chambers of Commerce (BCC), and involved 3,249 businesses.