RUTH Davidson failed to condemn Boris Johnson’s comments that Theresa May’s Brexit plan left the UK strapped to a “suicide vest” – despite one Tory minister describing the remarks as “disgusting”.

Critics said the comments insulted the real victims of suicide bombers, demonstrating no regard for their suffering.

The Scottish Tory leader was challenged to speak out and distance herself from the former foreign secretary, who is said to be positioning himself to challenge May as Tory leader.

Ian Blackford, the SNP’s Westminster leader, urged the PM to respond to Johnson and his fellow hard line Brexiteers by backing continued membership of the single market and customs union.

With Brexit fast approaching next March and just a couple of months before a deal has to be reached between the UK and EU, Blackford said: “The UK Government only has 200 days left before they drag us out of the EU.

“But we shouldn’t lose sight of the fact they’ve already spent over 800 days fighting over the shape of Brexit – essentially a debate on what degree of harm they are prepared to inflict upon our economy.

“And whatever deal is ultimately reached, the bitter infighting will leave the Tories a deeply damaged party at the end of the process.

“What the Prime Minister must not do is listen to the increasingly frenetic noises coming from the Brexit ultras on the Government benches. While Boris Johnson might be trying to stake a claim to the Tory leadership – an unconscionable prospect – his vision for Brexit would result in significant loss to our economy, jobs thrown on the scrapheap and businesses going bust.”

Christine Jardine, the Scottish Liberal Democrat’s Europe spokeswoman, hit out.

She said: “This choice of language and comparison from Boris Johnson is beneath contempt and shows no regard at all for those whose lives have been destroyed by suicide bombers. The Scottish Conservatives should distance themselves immediately. This is completely unacceptable from any MP never mind one who still seems to be regarded by some Tories as a potential PM.”

Shadow Scotland Secretary Lesley Laird said Davidson must use any influence she has on the party to ensure Johnson never returns to government or a senior position in the Tory party.

“Boris Johnson’s comments may have been an attempt to shock and ensure that he remains in the media spotlight but they are thoughtless, senseless and heartless comments to make barely a year on from the tragic events in Manchester,” she said.

“The comments are even more disappointing coming from a man who held a great office of state. Boris Johnson should never hold a position of power in government or the Tory party again, and it is incumbent on politicians like David Mundell and Ruth Davidson to ensure, for the benefit of Scotland and the whole of the UK, that he never does.”

Home Secretary Sajid Javid and Housing Secretary James Brokenshire both condemned Johnson’s language, saying it struck the wrong tone.

Writing in the Mail on Sunday, Johnson said talks so far had shown “Brussels gets what Brussels wants”, while hitting out at the “humiliation” of the Prime Minister’s Chequers deal and blasting the EU’s Irish border stance.

“We have wrapped a suicide vest around the British constitution – and handed the detonator to Michel Barnier,” he wrote

“We have given him a jemmy with which Brussels can choose – at any time – to crack apart the Union between Great Britain and Northern Ireland.”

Asked on the BBC’s Andrew Marr show if he believed the language was acceptable, Javid replied: “I think there are much better ways to articulate your differences.

Speaking on Sky’s Ridge on Sunday, Brokenshire echoed his Cabinet colleague’s remarks, saying: “I think he is wrong on this. I think the tone that he has used isn’t right and I think that we just need to be very focused on actually moving forward with the Chequers plan.”

Johnson’s comments sparked a backlash on social media, with Foreign Office Minister Sir Alan Duncan branding the comparison “one of the most disgusting moments in modern British politics”.

The Scottish Tories have denied rumours Davidson will move to London in the near future to pursue the party leadership. She reportedly told friends she would make the move as a stepping stone and abandon Scottish politics to take a peerage instead.