It came as SNP MP John McNally brandished a red card during Prime Minister's Questions amid critics of Mr Ross, saying members of the public were "expected to turn up to their day jobs or face sanctions".

Moray MP Mr Ross will not take part in a debate and vote on universal credit because he will be running the line at the Camp Nou Stadium in Barcelona as the home side take on the Greek team Olympiacos.

The game kicks off at 7.45pm UK time - 45 minutes after MPs at Westminster are expected to vote on a Labour motion calling for the controversial rollout of the new benefit to be postponed.

Mr McNally, producing a red card from his pocket, asked the Prime Minister: "Does the Prime Minister notice that I am wearing a red card in my pocket today?

"She will be aware that the honourable member for Moray is not in his place. Indeed, he is in Barcelona doing his other job, today of all days.

"What signal does she think this sends to hard working members of the public, who are expected to turn up to their day jobs or face sanctions?"

In reply, Mrs May said: "I think the constituents of Moray will be very pleased that they have a Conservative Member of Parliament who is seeing their interests in this House.

"And I can say to him that the Conservatives, the Scottish Conservative members, are doing more for the interests of Scotland in this Parliament than the Scottish nationalists have ever done."

Fellow Scottish Conservative MP Andrew Bowie had earlier defended his colleague, saying Mr Ross had personally raised concerns with Work and Pensions Secretary David Gauke.

Mr Bowie, speaking on BBC Radio Scotland's Good Morning Scotland programme, said: "I think the people of Moray are quite happy for him to continuing refereeing as well as being their MP and he's doing a very good job at both."

He spoke out after shadow Scotland Office minister Paul Sweeney accused Mr Ross of having a "perverse sense of priorities".

The Labour MP said: "The rollout of Universal Credit has blighted lives across the country, forcing many to rely on food banks and crisis grants to get by.

"Yet Mr Ross doesn't even have the decency to turn up to Parliament and explain why he supports putting people through such misery.

"This sorry episode will leave Mr Ross's constituents in no doubt as to where his priorities lie and it's not playing the game for them."

But Mr Bowie added: "Douglas has held over 50 surgeries since becoming a Member of Parliament, I think the people of Moray still back him as their Member of Parliament, as has been proven by he takes up their cases, he has spoken to David Gauke personally.

"Douglas has made concerns known and talked to David Gauke separately at various other places around Westminster. There will be many other Scottish Conservatives in the debate this afternoon."

Mr Ross has been an MP since June, when he ousted the SNP's Westminster leader Angus Robertson to win the Moray seat.

Prior to that he had served as an MSP at Holyrood, and had come under fire there after he missed a meeting of the Justice Committee in November 2016 to travel to Portugal to be assistant referee at a Champions League clash between Sporting Lisbon and Real Madrid.

In the Commons register of interests, Mr Ross has declared earnings of more than £2,700 for his work as an assistant referee in Scotland and Europe.

SNP MSP Stewart Stevenson hit out at Mr Ross saying: "Part-time Tory MP Douglas Ross just never learns his lesson - and he is yet again leaving his constituents without a voice in Parliament because he'd rather rub shoulders with famous footballers.

"This isn't the first time that he's failed to turn up for important meetings, and his constituents will be wondering why he shows no interest in discussing universal credit - which is driving up rent arrears and leaving families penniless.

"It's time for two-job Ross to call time on his highly lucrative refereeing career."