Theresa May has been blamed for “chaotic” preparations for a no deal Brexit as a row broke out in Whitehall over how to advise businesses to get ready for the possibility.

Civil servants have been ordered to compile 70 “technical notices” by the end of this month to explain to firms and self-employed workers what they need to do to be ready for Britain leaving the EU without a deal.

But ministers have complained that they were not consulted before Mrs May made an announcement about the technical notices last month, and officials are grumbling that they are having to draw up extra documents “just to make the numbers fit”.

Downing Street insisted that planning for the notices had been going on for months before Mrs May spoke publicly about them in July, and that each of the 70 areas had been carefully mapped out.

The Government’s current plan is to publish the advice papers in three batches in consecutive weeks starting on or around August 20.

Following comments by Liam Fox, the International Trade Secretary, that a no deal Brexit is now a “60-40” likelihood, the documents are more keenly awaited than ever by business leaders who want to make sure they take all necessary steps to protect their firms against the UK crashing out of the EU without a deal.