BORIS Johnson has rejected demands to recall of Parliament following warnings that a No-Deal Brexit would cause “incredibly serious” economic harm.

Fresh concerns have been raised following the leak of a confidential Whitehall dossier on the Operation Yellowhammer contingency plans.

The leader of the Confederation of British Industry (CBI) said it was impossible for firms to be fully prepared for the disruption that would occur following the UK crashing out of the EU without a deal.

More than 100 MPs have signed a letter demanding the Prime Minister cut short Parliament’s summer recess and Jeremy Corbyn has vowed to bring a vote of no confidence against the Tory Government.

But Downing Street rejected the demands, saying MPs had voted for the recess dates which will see Parliament return on September 3.

Johnson, who is scheduled to have face-to-face talks with Angela Merkel and Emmanuel Macron later this week, also acknowledged there was a “reluctance” in Europe about his demands for the backstop – the plan to prevent a hard border with Ireland in all circumstances – to be scrapped. “There may well be bumps in the road, but we will be ready to come out on October 31 deal or no deal,” Johnson said during a visit to Truro. “Now, of course, our friends and partners on the other side of the Channel are showing a little bit of reluctance at the moment to change their position. That’s fine – I’m confident that they will – but in the meantime, we have to get ready for a No-Deal outcome.

“I want a deal. We’re ready to work with our friends and partners to get a deal, but if you want a good deal for the UK, you must

simultaneously get ready to come out without one.”

Michael Gove, the Government minister in charge of No Deal planning, is expected to update MPs on developments when the Commons resumes sitting.

The National: Michael Gove visit to Northern Ireland

The leaked Operation Yellowhammer papers warned that Britain will be hit with a three-month “meltdown” at its ports, a hard Irish border and shortages of food and medicine if the UK leaves without an agreement.

Downing Street said the leaked dossier was “out of date” and “we are making all necessary preparations ahead of October 31”.

A spokeswoman said: “In recent weeks we have significantly stepped up our preparations for leaving the EU across a whole range of areas.”

A “large-scale public information campaign” is expected to begin shortly, No 10 said, with TV, radio, print and social media advertising. Upgrades to website have been made to cope with an expected surge in online traffic.

Johnson will meet German chancellor Merkel tomorrow and French President Macron on Thursday ahead of a G7 gathering in Biarritz on Saturday.

“He has been clear that there cannot be any actual negotiations unless the backstop goes and that’s the message he has delivered to leaders in his phone conversations, and he will do that face-to-face,” the Downing Street spokeswoman said.

“We have been clear that what the EU needs to understand is that unless the Withdrawal Agreement can be reopened and the backstop abolished, there isn’t any prospect of a deal.”

CBI director-general Dame Carolyn Fairbairn said the Government should focus on getting a Brexit deal because failure would come with a significant cost.

She told BBC Radio 4’s Today programme: “I think we can be prepared, we should be prepared, but I don’t think that takes away from the fact that what Yellowhammer shows, and I think what businesses have been saying for three years, is that the cost will be really significant for our economy and for jobs and that a deal is the number one priority.”

Jeremy Corbyn, meanwhile, has said a general election triggered by the Brexit crisis will provide a “once-in-a-generation chance” for change.

Speaking at a children’s centre in Northamptonshire, the Labour leader sought to set out his vision for the UK – in a speech which did not mention Scotland. He pledged to bring a vote of no confidence in the Tory Government. If successful, Corbyn says he will seek to form a “time-limited caretaker administration to avert No Deal” and will call a General Election.