The European Union has been urged to do a Brexit deal with Britain “before it’s too late” or face Boris Johnson taking the country out without a deal if he wins the next election, former foreign secretary Jeremy Hunt has said.

“If Boris wins, which is what the polls are saying at the moment, and he comes back with a majority, that British government will be much less willing to compromise,” the ex-cabinet minister told BBC political editor Laura Kuenssberg.

“That will make no-deal much more likely and that would make future relations between the UK and the EU much, much more problematic.”

In a pointed warning, he said: “If they think this is bad, just wait until what happens after Boris wins an election.”

Meanwhile, Business Secretary Andrea Leadsom has said the Government will not accept a backstop on Northern Ireland in any form.

Speaking on ITV’s Peston programme, Ms Leadsom said the backstop would not be entertained by a Johnson Government even for a limited time.

Mr Hunt, the runner-up in the Tory leadership race also accused European leaders of “miscalculations” in their dealings with Britain, and urged them: “Do something now before it’s too late.”

Mr Hunt’s comments will be read as an endorsement for Mr Johnson’s “two borders” proposals for removing the backstop from the Withdrawal Agreement by even the more moderate wing of the Conservative Party.

The PM wants Northern Ireland to approve plans to keep the six counties in line with EU rules on goods and agriculture, but take it out of the European customs union along with the rest of the UK – a move that would require checks on cargo moving within the island of Ireland.

Irish prime minister Leo Varadkar has said he is opposed to Northern Ireland being in a different customs territory from the south.

Mr Johnson is due to meet Mr Varadkar for what was described as a “private meeting” on Thursday at a location in the north west of England.

The meeting is to allow “detailed discussions” with their teams on the process for securing a deal, Downing Street confirmed.

Mr Hunt put pressure on Mr Varadkar to back down on talk of keeping Northern Ireland more closely aligned with EU rules and its custom regime.

“If Ireland’s real objective here is to keep Britain in the single market or keep Northern Ireland in the single market or reverse Brexit, then we’re not going to find a solution, and that will be when we have the real risk to peace,” he warned.

His comments came as Ms Leadsom hinted the PM was gearing up to by-pass legal obstacles to a no-deal Brexit by sending one letter requesting an extension and, in the same instance, submitting a second memo telling European leaders he does not.

The Benn Act demands the PM request a delay to the Article 50 deadline until January 2020 if a deal has not been agreed before October 19.

Mr Johnson has repeatedly said that while he will abide by the law, he will be taking the UK out of the EU on October 31, with or without a deal.

Asked on Peston whether the idea of sending two letters to the EU was a possible loophole, Ms Leadsom replied: “Absolutely.”

She also said the current government would not accept a backstop on Northern Ireland.

“The point is, Parliament voted against the backstop that was in the previous withdrawal agreement three times,” she said. “So Parliament won’t wear it, so the Government, this Government, has made clear that we will not accept the backstop.”

Asked if “even a time-limited backstop” was not acceptable, Ms Leadsom replied: “That’s right.”

In Brussels, there was fury in the European Parliament when the chamber’s President David Sassoli confirmed he had met Speaker John Bercow to discuss the terms of an extension.

The Italian politician said an extension would be approved if it paved the way for a second referendum or a general election.

Mr Sassoli told MEPs: “I had a fruitful discussion with Speaker Bercow in which I set out my view that any request for an extension should allow the British people to give their views in a referendum or an election.”

But both Ms Leadsom and Brexit Party leader Nigel Farage hit out at the meeting between the men in London on Wednesday.

Ms Leadsom reminded Mr Bercow, who is due to stand down at the end of the month, of the importance of remaining neutral in his role.

She said it was “absolutely vital” the Commons Speaker was “seen to be impartial and to not be picking sides and to not be interfering in matters that are political”.

Mr Farage called the meeting “disgraceful” and fellow party member Belinda de Lucy MEP accused Mr Sassoli of “directly interfering” in British politics.

In a tense day in the Belgian capital, the parliament’s Brexit co-ordinator Guy Verhofstadt called Mr Johnson a “traitor” for his hardline exit strategy.

“All of those who are not playing his game are traitors, collaborators or surrenders,” said the former Belgian prime minister.

“Well, in my opinion the real traitor is he or she who risks bringing disaster upon his country, its economy and its citizens by pushing Britain out of the European Union.”

The EU’s chief negotiator Michel Barnier said there was still no basis for a deal on Britain’s withdrawal from the EU.

Ahead of next week’s crucial European Council meeting, Mr Barnier said they had yet to see any “operational, legally binding solution” to the issue of the Northern Ireland backstop.

He said Mr Johnson’s “two borders” proposals were based on a system “that hasn’t been properly developed, that hasn’t been tested”.

Mr Barnier’s downbeat assessment was echoed by Mr Varadkar, who said the Tory leader’s insistence that Northern Ireland must leave the customs union with the rest of the UK remained an obstacle to progress.

“That’s their position at the moment and that’s one that is a great difficulty for us,” he told the Irish Parliament.

“As far as the Irish Government is concerned, we do want a deal, we’re willing to work hard to get a deal, to work until the last moment to get a deal, but certainly not at any cost.”