Jacob Rees-Mogg was “wrong” to describe Scottish Conservative leader Douglas Ross as a lightweight, former MSP Adam Tomkins has said as a split looms in the party.

Mr Ross called for Prime Minister Boris Johnson to quit after he admitted attending a gathering in the Downing Street garden during lockdown in May 2020.

On Wednesday, the Leader of the House of Commons hit out at the Scottish leader, describing him during an appearance on the BBC’s Newsnight programme as “quite a lightweight figure” in the party.

Politics expert Professor Sir John Curtice said those comments “are going to get repeated endlessly north of the border” by the Tories’ opponents.

He warned: “Given the difficulties the Conservatives are now in, they are at risk of beginning to implode themselves as a result of the internal fighting within the party.”

Sir John, speaking on BBC Radio Scotland’s Good Morning Scotland programme, said the upcoming council elections north of the border could help explain why Tories in Scotland are speaking out against Mr Johnson – with the overwhelming majority of MSPs having publicly backed Mr Ross and his calls for the PM to quit.

The Strathclyde University elections expert said Scottish Conservative Party “knows it is on a sticky wicket” with the local elections in May.

While he said the Tories will “not want to be fighting those elections against a backdrop of a party that has lost its popularity”, he added: “That at the moment is the prospect that faces it.

“Which perhaps helps to explain why Tory MSPs have been the first out of the hatch to say that the Prime Minister should go.”

A spokesman for the Scottish Conservatives insisted the party has “nothing to say about Mr Rees-Mogg”, but former MSP Adam Tomkins insisted he was “wrong” to brand Mr Ross a “lightweight” – describing it as “very rude and dismissive”.

Meanwhile, No 10 said the UK Government was focussing on actions to “strengthen the union” with the announcement of an agreement between the UK and devolved Governments that the Pm would chair a new council.

The Prime Minister’s official spokesman was asked whether Mr Rees-Mogg’s comments undermined the efforts, and he said: “No, I think you can see what we’re doing on the union by what Michael Gove has set out just today on the review into inter-government relations, which seeks to take tangible action to strengthen our union.”

But Professor Tomkins added there is now some “serious thinking” that needs to be done in Scotland about the links between the party on either side of the border.

Prof Tomkins told Good Morning Scotland: “There’s a ‘Save Boris’ operation going on at the moment, which you would expect Jacob Rees-Mogg to be… at the head of. That explains why Jacob Rees-Mogg was very rude and dismissive about Douglas yesterday.

“Jacob’s got this wrong – I don’t agree with anything that Jacob said about this matter.

“Douglas is a man of principle and a man of steel, and he will lead the Scottish Conservatives in the direction he thinks he needs to lead them in order to secure that credible fighting voice for centre-right ideas in Scottish politics.”

Under questioning in the Commons on Thursday, Cabinet Office minister Steve Barclay described Mr Ross as a “hugely talented colleague”, adding: “I work extremely closely with him and I look forward to doing so”.

Prof Tomkins, who quit Holyrood last year but remains a major figure in the Scottish Conservatives, hinted at a growing schism between the Tory party at Holyrood and Westminster and a possible shift in their relationship.

“I think there will always be ties but I think that Douglas and his team need to do some deep and serious thinking about exactly what the nature of those ties should be,” he said.

“All of the bad days the Scottish Tories have in Holyrood are not caused by the Scottish Tories in Holyrood, they are caused by events 400 miles south. And they need to reflect on that.

“The Scottish Conservative Party have a range of really important, substantive ideas to bring to the table in Scotland about economic policy and about social policy, and they are being drowned out because of the pantomime of the politics of Boris Johnson.”

The SNP seized on the comments on Wednesday, claiming they show “disdain for Scotland”.

Kirsten Oswald, the party’s deputy leader at Westminster, said: “Not only is it deeply humiliating for Douglas Ross but it is a telling insight into the arrogant and dismissive attitude that the Tory Government has towards Scotland as a whole.

“They are looking down their noses at us and making it clear just how little Scotland’s views matter to them – just like they did over Brexit and Tory austerity cuts.”

She added: “As the UK Government descends into another bitter Tory civil war, it’s clearer than ever that Scotland needs to become an independent country, so we can determine our own future and escape the sleazy, corrupt and broken Westminster system for good.”