Viewers of BBC Question Time have taken to social media to slam the corporation's flagship show after a former Tory MSP appeared as part of the show's audience. 

The SNP's Stewart McDonald pointed out that former Conservative MSP, Mary Scanlon had made an appearance during the show in Elgin, sparking a fresh row over the BBC's vetting process for the show.

READ MORE: BBC Question Time criticised over balance as panel show visits Elgin

The 71-year-old former member of the Scottish Parliament for the Highlands and Islands spoke on the future of the Conservatives and the need for a UK leader that would unite the party and the country. 

Many were quick to spot the former MSP and raise her appearance on social media.

Stewart McDonald tweeted: "Why is former Tory MSP Mary Scanlon - 1999 to 2016 - pretending to be an audience punter on #BBCQT?"

His tweet has since been retweeted by the SNP. 

READ MORE: "More plants than a Garden Centre" - Twitter reacts to alleged bias on BBC Question Time 

Responding to Mr McDonald, Conservative MSP Edward Mountain said: "I think, as she is no longer an MSP, that she is just a voter. I also know she will have been through the audience vetting process."

The BBC has been accused in the past of bias in Scottish Question Times with the show being forced to defend its vetting process after it emerged that former UKIP candidate Billy Mitchell had appeared on the popular politics show 4 times. 

READ MORE: BBC Question Time slammed after former UKIP candidate makes audience appearance for fourth time

The application form requires prospective guests to say whether they have previously been on the show, and when.

Guests must also reveal who they would be most likely to vote for in a General Election, how they voted in the EU referendum, and whether they are a  member of a political party. 

Deputy First Minister John Swinney of the SNP, Scottish Labour leader Richard Leonard and Edinburgh West MP Christine Jardine of the Lib Dems were among those on the show. 

Responding to the criticism over the audience selection, a spokesperson for the BBC said: “Question Time does not bar people from its audience because they have held elected office or are political activists.

“There is a selection process to ensure a range of views are heard and last night’s QT audience included supporters of different political parties, including the SNP.”