THE SNP have written to two Westminster watchdogs calling for an investigation to be opened into embattled Scottish Tory leader Douglas Ross.

Ross, who has announced he will resign as Scots group leader after the General Election, has been fighting fires on two fronts after he U-turned on a pledge not to run to be an MP.

Ross said he would run in Aberdeenshire North and Moray East, where local members had already selected David Duguid to run, sparking anger at the deselection of a sick man.

The backlash within the Tories led to insiders briefing against Ross to the media, revealing he faced questions about the use of parliamentary expenses and his refereeing work.

The pressure over the dual scandals forced Ross to say he will quit as Scottish Tory chief, in what was understood to be the first time a UK party leader has resigned during a General Election campaign.

Now, the SNP have said a “swift investigation is required because of the fact that Ross is now seeking re-election to Westminster”.

In a letter to the Independent Parliamentary Standards Authority and the Parliamentary Commissioner for Standards, SNP depute leader Keith Brown wrote: "On Sunday, a substantial and serious allegation emerged regarding Douglas Ross, the Tory MP for Moray in the outgoing parliament.

"Mr Ross is in the highly irregular position of possessing three different paid jobs at the same time – MP, MSP, and football linesman.

READ MORE: Who is in the running to replace Douglas Ross as leader of the Scottish Tories?

"According to the Sunday Mail, a whistleblower in the Tory Party has alleged that Mr Ross abused his publicly paid expenses as an MP to fund and facilitate his paid employment as a football referee – and then sought to cover it up.

"The Sunday Mail reports, ‘his team identified the 28 [claims] where he wrongly used parliamentary-funded travel to facilitate ref work’, including ‘multiple cases where Ross had combined parliamentary travel with linesman work or claims for parking while refereeing on expenses’. These claims were allegedly ‘hushed up by worried aides’.

"If confirmed, this would amount to a serious breach of the MP Code of Conduct, with Section D, Rule 2 clearly stating: ‘Members must base their conduct on a consideration of the public interest, avoid conflict between personal interest and the public interest and resolve any conflict between the two, at once, and in favour of the public interest.’

"If these allegations were fully substantiated, it would mean that Mr Ross has been abusing his public funded Westminster expenses to unfairly fund his receipt of another, separate salary. It would amount to another Westminster expenses scandal carried out by the current leader of the Scottish Tory Party."

(Image: PA)

Brown (above) went on: "Given the seriousness of this matter, it is in the public interest for these allegations to be investigated immediately.

"The need for that swift investigation is also required because of the fact that Mr Ross is now seeking re-election to Westminster, due to his last-minute decision to displace his colleague David Duguid.

"Voters in Aberdeenshire North and Moray East have the right to know if Douglas Ross has blatantly abused publicly paid expenses over the last number of years.”

Speaking to the BBC on Tuesday morning, Ross said he would be content with the Independent Parliamentary Standards Authority assessing whether there was any wrongdoing in his Westminster expenses claims.

The Parliamentary Commissioner for Standards cannot investigate complaints about the conduct of candidates during the election campaign.