SNP Westminster deputy leader Mhairi Black has rejected the idea that the SNP leadership contest has been anything but fair and above board.

Speaking on ITV’s Peston on Wednesday night, Black's comments came just before leadership hopefuls Kate Forbes and Ash Regan called for independent auditors to be brought in to oversee the SNP leadership ballot, calling into question the integrity of the leadership race.

Humza Yousaf, meanwhile, has accused his rivals of “baseless smears.”

READ MORE: SNP leadership contest escalates into row – follow it LIVE

All three contenders' camps, and a host of senior parliamentarians, have called on the SNP HQ to publish the party’s membership figures.

Black was also questioned by Peston on the “infighting” that has sometimes characterised the SNP leadership contest.

The SNP MP said it was “bizarre” and compared it with previous discord within the Tory party.

“It looks like we’ve taken a leaf out of your book,” she said to Jake Berry, a Conservative MP and former chair of the Conservative Party, who joined her on the show.

The National:

Black added that she welcomed robust debate within the party. She said: “There's a balance to be struck. In any leadership contest, there’s an element of discomfort because people have to get their own ideas across, their own styles across.”

Peston also remarked on what he called the SNP’s “broad church.” He asked: “The Tories have been alleging that you’re all lefties but you're not all lefties are you?”

Black responded: “That is one of the things I kinda like about the SNP at times. That we’re able to have these robust debates and argue things amongst ourselves before we take it to the public.

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“I’ve made no secret of the fact that I think that the SNP’s success has been built on our progressive agenda, on the fact that we’re relentlessly positive in trying to deal with the day-to-day issues that are really affecting people’s lives.

“So long may that continue no matter who’s First Minister.”

It comes as Scottish Deputy First Minister John Swinney said he doesn't understand why there's a row, insisting he is “100%” sure it is being conducted properly.