A Scottish Tory who chose to referee a football match rather than vote in a key welfare debate "may feel his time is better spent elsewhere", according to the Prime Minister's spokesperson, who backed his decision.

Douglas Ross, the MP for Moray who defeated Angus Robertson in June, will be an assistant referee in the Champions League match between Barcelona and Olympiakos at the Nou Camp this evening.

That means he will miss a key debate on the rollout of Universal Credit in Westminster today. But Theresa May's spokesman appeared to have no problem with Ross's decision to go to Barcelona instead.

WATCH: SNP MP shows Theresa May the red card as Scottish Tory referee MP Douglas Ross misses key welfare vote

"On some of these debates we may say to MPs if you feel your time can be better spent elsewhere, then ..." the spokesman was reported as saying. "You will see Tory MPs who take an interest in this speak in the debate and of course you will have ministers speak from the Despatch Box."

SNP MSP Stewart Stevenson said it was time for "two-job" Ross to call time on his refereeing sideline.

"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," he said.

"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."

May has rejected calls to pause the roll-out of Universal Credit as ministers announced that controversial charges of up to 55p a minute to call a helpline were to be scrapped.

At Prime Minister's Questions, May insisted that the overall system was working and she dismissed a call by Jeremy Corbyn for a delay to "fix" the problems.

The Labour leader, who highlighted the helpline charges in the House last week, told her: "The fundamental problems of Universal Credit remain. The six-week wait, rising indebtedness, rent arrears and evictions."

However, May said: "It is a simpler system. It is a system that encourages people to get into the workplace. It is a system that is working because more people are getting into work."

The exchanges came as Labour sought to highlight concerns among Tory MPs over the roll-out of Universal Credit with an opposition day debate on the issue.