In an exclusive interview with BBC political editor Laura Kuenssberg, Mr Johnson said the current withdrawal agreement "is dead", but stressed the UK has to leave the European Union on October 31.

While admitting that there is no "single magic bullet" to ensure there are no checks on the border after Brexit, he said a "wealth of solutions" exist that would solve the problem.

"There are abundant, abundant technical fixes that can be introduced to make sure that you don't have to have checks at the border. That's the crucial thing. And everybody accepts that there are ways you can check for the rules of origin, there are ways you can check for compliance with EU goods and standards, of our goods standards," he said.

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Boris Johnson MP. Pic: PA

Pushed by Laura Kuenssberg that no such solutions yet exist, Mr Johnson continued: "Well, they do actually, in very large measure they do. You have trusted trader schemes, all sorts of schemes that you could put in to place.

"You're right, Laura, that there's no single magic bullet. But there is a wealth of experience, a wealth of solutions. And what's changed now is that there is a real positive energy about getting it done."

The Tory leadership hopeful, who has been branded "a coward" for refusing to take part in a TV debate against his opponent Jeremy Hunt, later added: "There are plenty of checks that you can do away from the border if you had to do them without any kind of hard infrastructure at the Northern Ireland frontier."

Asked if he would give a guarantee the UK will leave the EU at Halloween, even without a deal, Mr Johnson said: "My pledge is to come out of the EU at Halloween on 31 October. And the way to get our friends and partners to understand how serious we are is finally, I'm afraid, to abandon the defeatism and negativity that has enfolded us in a great cloud for so long and to prepare confidently and seriously for a WTO or no deal outcome.

"You've got to understand, Laura, listening to what I just said, that is not where I want us to end up. It is not where I believe for a moment we will end up. But in order to get the result that we want, in order to get the deal we need, the commonsensical protraction of the existing arrangements until such time as we have completed the free trade deal between us and the EU that will be so beneficial to both sides. The commonsensical thing to do is to prepare for a WTO exit."

Later in the interview, Mr Johnson again stressed that there will be no hard border on the island of Ireland.

"In the real world, the UK government is never going to impose checks or a hard border of any kind in Northern Ireland. That's just number one. Number two in the real world the UK government is not going to want to impose tariffs on goods coming into the UK.

"It's not just up to us, it's up to the other side as well. And there is an element of course, a very important element of mutuality and co-operation in this. And we will be working with our friends and partners to make sure that we have an outcome that is manifestly in the interests of people, of businesses, communities on both sides of the channel."