DOUGLAS Ross has said that Boris Johnson should "of course" resign if he is found to have broken the ministerial code.

As probes are under way into whether the Prime Minister properly declared donations for lavish refurbishments to his Downing Street flat, the Scottish Tory leader was quizzed on his stance.

He was asked on the BBC’s Andrew Marr show if Johnson should quit if found to be in breach of the ministerial code, with Ross having previously called for the resignation of SNP leader Nicola Sturgeon if she had broken the rules.

“Of course, I think people expect the highest standards of those in the highest office of the land, that’s why I think people are looking at the investigations that are currently ongoing and waiting for the answers,” Ross said.

The Electoral Commission this week launched an investigation into whether any donations or loans to pay for the refurbishment of Johnson's residence in No 11 Downing Street were properly declared.

But new standards adviser Lord Geidt has also been tasked with reviewing the controversy, in an investigation expected to touch on whether he has breached the ministerial code.

Nicola Sturgeon was cleared of a potential breach of the ministerial code in March by top Irish lawyer James Hamilton.

There were concerns about the First Minister's recollection of a meeting with former First Minister Alex Salmond over complaints regarding her predecessor.

Concerns revolved around a delay in the date of Sturgeon first finding out about complaints and what she told parliament about her recollection.

Hamilton found that there was no breach of the code by the First Minister and her initially forgetting the recollection of discovering the news about Salmond did not amount to misleading parliament.

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Foreign Secretary Dominic Raab (above) defended Johnson on Sunday but declined to say whether the Prime Minister should resign if he is found to have broken the law by the Electoral Commission.

“I think the right thing for me to do is respect the integrity of those reviews and let them run their course rather than commenting on what may or may not be found at the end of it,” he told Marr.

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Raab declined to deny a claim that a second invoice for lavish renovations of the Prime Minister’s residence in No 11 may have been settled with the supplier by a Tory donor.

And he was asked about the suggestion in The Sunday Times that an MP received a complaint from a Tory donor that they were asked to pay for a nanny for Johnson’s one-year-old son Wilfred.

“I have no idea, you don’t have conversations like that with the PM,” he told Sky’s Sophy Ridge On Sunday, as he derided the claim as “tittle-tattle”.

A No 10 spokesperson said the Prime Minister “has covered the cost of all childcare”, but did not respond when asked if he paid for the original bill himself or had reimbursed somebody else.