THE SNP has called on the BBC to refer itself to Ofcom, the independent broadcasting regulator, over its “credibility problem” with audience vetting for its flagship political debate programme Question Time.

Keith Brown, the party’s deputy leader, expressed alarm about the political balance of the audience during Thursday night’s edition, recorded in Elgin.

The audience included Mary Scanlon, who served as a Tory MSP in the Scottish Parliament for more than 10 years, as well as several Conservative councillors and local party office bearers, stressed the SNP.

Ms Scanlon, 71, the former MSP 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.

The BBC has previously been accused of bias in Question Times broadcast from Scotland with the show being forced to defend its vetting process after it emerged that Billy Mitchell, the former UKip candidate, had appeared on the popular politics show four times.

Mr Brown accused the programme of having a “credibility problem” and said Thursday night’s audience went completely against the ethos “that politicians answer questions posed by members of the public”.

“The BBC has a duty not to mislead its audience. The fact is the BBC’s flagship debate programme, week after week, has elected politicians and political activists masquerading as ordinary members of the public. It seriously undermines the whole ethos of the programme,” he declared.

“At any time, there would be serious questions to answer about credibility but just days away from the European elections these matters strike at the very heart of the BBC’s ability to fulfil its statutory and elections obligations…

“Following a similar incident in February, we pleaded with the BBC to be transparent about the processes around audience selection for Question Time, instead they’ve been defensive and refuse to admit mistakes. Enough is enough,” insisted the MSP for Clackmannanshire and Dunblane.

Mr Brown added: “The BBC should refer itself to Ofcom and allow them to hold an independent investigation. That’s the only way we’ll get to the heart of whether the individuals identified in the Elgin audience lied on their application forms or whether the BBC knowingly allowed these individuals to masquerade as members of the public.”

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

He stressed how audience members had been selected for last Thursday’s programme to ensure a range of views was heard and the audience had “included supporters of different political parties, including the SNP”.

John Swinney, the Deputy First Minister, Richard Leonard, the Scottish Labour leader and Christine Jardine, the Liberal Democrat MP for Edinburgh West, were among those on the show.