A consultant for the SNP met the controversial data firm Cambridge Analytica in the run up to the last Holyrood elections, the First Minister has revealed.
But Nicola Sturgeon stressed while the meeting took place in February 2016 the "fundamental point" was the company had not done any work for her party or the Scottish Government.
Ms Sturgeon said: "The SNP has never worked with Cambridge Analytica, we've never hired them, we've never paid them any money to do any work for us."
She hit out after coming under pressure from Tory leader Ruth Davidson over the meeting, with the Conservative claiming it "looks pretty shifty" the SNP has not fully answered opposition questions on the matter.
Raising the issue at First Minister's Questions at the Scottish Parliament, Ms Davidson demanded to know when exactly the meeting took place, where it was held, and who was the consultant representing the SNP.
"These are very simple questions to someone who is committed to full transparency," the Tory leader said.
Ms Sturgeon revealed the meeting took place in February 2016 - but she refused to name the consultant who represented the SNP in case it sparked a "witch hunt".
The First Minister insisted: "I am not going to name somebody who was working for the SNP as a consultant, somebody who has done nothing wrong."
And during noisy exhanges in Holyrood the SNP leader also claimed it was the Conservative Party "mired in links to Cambridge Analytica".
The company has been under fire over the use of Facebook users' personal data in Donald Trump's race for the US presidency.
Earlier this week Brittany Kaiser, who was the firm's business development director revealed that while they had not done any work for the SNP there had been "pitches and negotiations" at meetings in London and Edinburgh.
In response an SNP spokesman said an external consultant had had one meeting in London and judged the firm to be "a bunch of cowboys" - with no work having ever been carried out by Cambridge Analytica for the party.
Ms Davidson said: "When it comes to dealings that others have had with Cambridge Analytica, the First Minister and her party have spent weeks demanding full transparency.
"Yet when it comes to the SNP it took a whistleblower giving evidence in a parliamentary committee before facts even began to be dragged out into the open."
She stated: "Now I know the SNP have raised sanctimony to an art form but what stinks here is the reek of hypocrisy."
But the SNP leader hit back, claiming the links between the Conservatives and Cambridge Analytica and its parent company SCL "are many and legion".
She went on to challenge Ms Davidson to say if any of the reported dealings between either the UK Conservative Party or the UK Government and Cambridge Analytica were untrue.
SNP backbencher George Adam has also now written to the Scottish Conservative leader to demand which reports she disputes.
He said: "During First Minister's Questions you very carefully qualified your claim that your party hadn't had any communication with Cambridge Analytica - referring only to the Scottish Tories, rather than the parent organisation.
"As you have demanded transparency from others, will you now confirm whether your party, at any level - and not just the Edinburgh office - have met with, hired or in any capacity employed Cambridge Analytica?"
Afterwards Labour MSP Neil Findlay later said the First Minister had "revealed today that the SNP met with this firm in February 2016, months before the Holyrood elections".
He added: "Only in the world of the SNP could refusing to answer who was at the meeting and what was discussed could possibly be considered transparent."