File photo. Photograph:( Others )
The Institue of Directors (IoD) said on Friday, less than a third of 800 UK business leaders surveyed have carries out contingency planning on Brexit.
The survey showed that global firms that trade with both EU and non-EU countries were more active in contingency planning.
Forty-two per cent will make changes only once the relationship between Britain and EU becomes clearer and 49 per cent did not expect to be affected by Brexit.
"Many companies are still unprepared for Brexit, and it’s hard to blame them," said Stephen Martin, IoD director general.
"When it comes to knowing what to plan for and when, firms have been left in the dark," he added in a statement.
"As long as no-deal remains a possibility, it is essential that the government steps up to the plate and provides advice on preparing for such an outcome. We therefore urge them to speed up publication of the technical notices.''
The notice on no-deal preparations will be out by August and September, Prime Minister Theresa May's government said.