The two sides aim to agree a deal on trade and future relations by the time of an October 15 meeting of EU leaders so that the agreement can be ready by the time the Brexit transition period expires at the end of the year.

"If we can’t agree by then, then I do not see that there will be a free-trade agreement between us, and we should both accept that and move on," Johnson will say Monday, according to a statement released to the press ahead of this week's round of negotiations, which begins Tuesday in London.

"We will then have a trading arrangement with the EU like Australia’s," Johnson added. "I want to be absolutely clear that, as we have said right from the start, that would be a good outcome for the U.K. As a government we are preparing, at our borders and at our ports, to be ready for it."

He also reiterated his call for the EU to offer the U.K. a trade deal similar to the one it has with Canada. The EU has countered, however, that given the U.K.’s geographical proximity and close ties with the bloc, such a deal is not possible.

"Even at this late stage, if the EU are ready to rethink their current positions and agree this I will be delighted," Johnson said. "But we cannot and will not compromise on the fundamentals of what it means to be an independent country to get it.”

The future relationship negotiations have hit deadlock as neither the EU nor the U.K. want to give in on state aid or fisheries — the two biggest sticking points preventing them from signing a deal. The prior round of talks ended in Brussels with almost no progress, boosting pessimism on both sides of the Channel.