A Perth Tory council hopeful previously backed independence and was still registered as a member of the SNP when he first stood for the Conservatives in a by-election less than two years ago.
Local businessman Aziz Rehman was expelled by the nationalists in October 2020 when it emerged his name was on the ballot for their unionist rivals.
Mr Rehman will stand for the Tories again in the Perth City North ward next month and has been pictured on the campaign trail with prominent party MSP Murdo Fraser.
He has vowed to help tackle anti-social behaviour, focus on mental health and keep the streets clean in his pitch to local voters ahead of the election.
But Labour claim his candidacy “makes a mockery” of Conservative claims that they are “champions of the union”.
‘I have moved from Yes to No’
Mr Rehman admitted he previously backed independence but insisted he is now “100%” against a re-run of the 2014 vote.
He claims he left the SNP before standing as a Conservative candidate but the party says he was dropped after being registered for the Tories.
Mr Rehman said: “I once supported independence long ago but I have moved from Yes to No.
“I would now describe myself as a strong unionist and a committed pro-UK supporter. I am 100% opposed to another referendum.”
Douglas Ross and senior Tories have repeatedly slammed Labour for supposedly being soft on preserving the union.
I am 100% opposed to another referendum.”
– Aziz Rehman
Conservative MSP Annie Wells said too many Labour candidates are in favour of “breaking up Britain”.
Earlier this year Anas Sarwar ruled out any prospect of his party running pro-independence hopefuls in the May 5 council vote.
Labour’s deputy leader Jackie Baillie said: “The facts are clear – the Scottish Tories are a danger to the union, not the saviours of it.
“That they would allow an SNP member to stand for them at this election makes a mockery of their claim to be champions of the union.”
Mr Rehman also signed a letter in The Herald just weeks before the 2014 referendum indicating his support for independence.
Perth and Kinross Labour councillor Alasdair Bailey said: “This revelation plainly shows that if the people of Perth want a councillor that is committed to the union, they have to vote Labour.
“Time and time again, the Scottish Tories have failed the people of Perth – this attempt to impose a pro-independence councillor is only the latest failing.”
An SNP spokesperson said: “Aziz Rehman’s membership of the party was suspended by SNP HQ on October 15, 2020, when it became apparent he was standing as a Conservative candidate in the Perth City North by-election.”