Craig Anderson, senior business partner at KPMG in Scotland, said:
It is clear that the business community is still seeking to have concerns allayed as we move closer to September 18.
Our research suggests that most businesses probably do not feel sufficiently informed to make appropriate long-term plans, with any action likely to be taken only when the outcome is known.
More top news
Through the day, most of the cloud should break up to leave fine conditions for many with spells of sunshine.
The Eiffel Tower in Paris was plunged into darkness, with the Burj Khalifa in Dubia emblazoned with the Union Jack.
The major party leaders' campaigns for the General Election will remain suspended on Wednesday following the Manchester terror attack.