Questions need to be asked over the selection of Michelle Thomson as an SNP candidate and the party's vetting procedures, according to political opponents.

Scottish Conservative leader Ruth Davidson said there was a question around the "probity" of the SNP's candidate selection while Scottish Labour said "real questions" have to be asked over the selection of Ms Thomson to stand for parliament.

At First Minister's Questions on Thursday, Nicola Sturgeon was challenged on her party's knowledge of the business dealings of Ms Thomson, now an MP.

It came after it emerged Ms Thomson is to help police with their inquiries into property deals conducted five years ago. She has been linked with deals involving a solicitor who has since been struck off.

Ms Thomson, who was this year elected as the member for Edinburgh West, has denied any wrongdoing and withdrawn herself from the party whip, a move which also means her membership of the SNP is suspended.

Ms Sturgeon told Holyrood the SNP did not know about MP's business dealings until reports began to emerge in the newspapers.

Questioned on the subject today, Ms Davidson told the BBC's Sunday Politics Scotland show: "I think there's a question here about the probity of their (the SNP's) candidate selection.

"It's incredibly difficult, all political parties have people that come to them and say they want to stand and you do the vetting as best you can.

"I think what people need to know is ... what kind of candidate vetting procedures went on in the SNP?"

Scottish Labour said "real questions" need to be asked over the selection of Ms Thomson.

Jackie Baillie MSP, Labour's public services spokeswoman, said: "Every day brings fresh embarrassment for the SNP over the selection of Michelle Thomson as a parliamentary candidate."

An SNP spokesman said: "This issue is under investigation by the relevant authorities, so Labour and the Tories should allow that to come to a conclusion and for all the facts to be examined - instead of indulging in mud-slinging and a rush to judgement."