Chancellor Philip Hammond has predicted a “constitutional crisis” if the next prime minister suspends Parliament to try and push through a no-deal Brexit.

In a thinly veiled warning to frontrunner for the Tory crown, Boris Johnson, the Chancellor said he would back legal moves suggested by ex-prime minister Sir John Major to challenge any prorogation of Parliament in the courts.

Mr Hammond told Bloomberg: “If anybody were to attempt to shut down Parliament in order to carry out a course of action which Parliament is known to oppose, that would be very serious indeed.

“That would provoke a constitutional crisis.

“And, if we aren’t able to prevent that course of action through Parliament, then, certainly, there will be resort to the courts, and I strongly support the position that Sir John Major has taken.”

Sir John Major
Sir John Major warned of legal action to challenge any prorogation of Parliament (Yui Mok/PA)

Sir John has threatened to drag Mr Johnson through the courts if he attempts to suspend Parliament in order to prevent MPs blocking a no-deal exit from the European Union in October.

Mr Hammond’s comments came as Business Secretary Greg Clark said a no-deal Brexit would lead to the loss of “many thousands” of jobs.

Mr Clark implored colleagues to “strain every sinew to avoid that”, with leadership rivals Mr Johnson and Jeremy Hunt both pledging to leave the EU without a deal if need be.

But the men vying to succeed Theresa May face a battle to force through their commitment, as some MPs vow to block any attempt.

Mr Johnson has pledged that he will enact the EU exit by the Halloween deadline “come what may, do or die”, while Foreign Secretary Mr Hunt said he would be willing to delay if a deal was in sight.

Tory leadership contest timetable
(PA Graphics)

Mr Clark warned in an interview broadcast on Friday that the disruption of a no-deal departure would lead to the shedding of jobs.

“It’s evident that if you have the disruption that comes from a no-deal Brexit there will be people that will lose their jobs,” he told Sky News.

“It’s many thousands of jobs. Everyone knows that.”

Mr Clark cited evidence from businesses when challenged that some are claiming the UK could weather an exit on World Trade Organisation terms.

“I think every person that considers the evidence that companies have given – whether it’s in the automotive sector, whether it’s in the food sector, whether it’s in aerospace, in industries up and down the country – you know if you become less efficient and your ability to trade is impeded, then of course losing your competitiveness means there will be jobs lost,” he said.

A spokeswoman for Mrs May told a Westminster briefing: “The Prime Minister has always been clear that leaving without a deal would be disruptive.”

The ability to leave the EU by October 31 has been a major issue in the Tory leadership contest.

Boris Johnson at the Tory leadership hustings in Maidstone
Boris Johnson at the Tory leadership hustings in Maidstone (Gareth Fuller/PA)

Mr Johnson has taken the tougher line, even refusing to rule out suspending Parliament to force through a no-deal against the wishes of MPs.

But he insisted at a Tory leadership hustings in Maidstone on Thursday that “common sense” would prevail among his colleagues, causing them to support his bid to sever the UK from the EU.

Mr Hunt, however, warned that “the big risk” facing the Conservative Party was ending up with an election and no departure “if we approach Brexit in a headstrong way”.

Labour is poised to prevent any attempt at a no-deal Brexit, as are senior Tories including Justice Secretary David Gauke.

But Work and Pensions Secretary Amber Rudd has offered some optimism for no-deal proponents, saying the move had to remain in the “armoury” of the next PM.

On Friday, the contenders head to Cheltenham for their latest hustings with the Tory members who are choosing their destiny.

Interviews with the BBC’s Andrew Neil will also be aired.

The new leader will be announced on July 23 and sworn in as PM the following day.