NICOLA Sturgeon has hit back at reports that she previously had concerns over former finance secretary Derek Mackay's conduct, calling them "completely and utterly without foundation".

While speaking to the BBC the First Minister was asked the resignation of Mackay, who quit the Government and was suspended from the SNP last week following allegations that he sent a 16-year-old boy hundreds of messages.

Sturgeon said she "felt utterly shocked and stunned at the revelations", originally reported in the Scottish Sun.

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She continued: "I make no bones about feeling a significant sense of upset and shock about that. But I’m the leader of my party, I’m the First Minister, and not withstanding those personal feelings my duty is to make sure that we respond decisively and appropriately, and that I believe is what the Scottish Government has done."

First Minister Nicola Sturgeon spoke to us this morning about her “sense of upset and shock” at Derek Mackay’s behaviour and shut down suggestions she had any pre-existing concerns about his conduct as being “utterly without foundation”@BBCScotlandNews pic.twitter.com/oTVeKJjAql — Natalie Higgins (@nataliesophia) February 10, 2020

The reporter than asked about newspaper claims that she had expressed concerns about Mackay's behaviour. "Is there any truth to that?" she asked.

Sturgeon said the suggestions were a "smear".

The SNP leader replied: "There is no truth in that whatsoever and I think any attempts to suggest I somehow knew of behaviour of this nature is an attempt to smear and I think says more about perhaps, opposition politicians that are trying to say that than it does about me.

"There was a reference to my telling Derek Mackay not to go out and socialise at party conferences. It was almost a running joke between us as a result of one morning when he was chairing conference, having been out late the last night he was a bit worse for wear, and I told him not to do it again. And it became a bit of a light-hearted thing between us at party conferences.

"But the suggestion that was in any way shape or form related to concerns that had been raised about his behaviour of that nature is completely and utterly without foundation."

Yesterday SNP depute leader Keith Brown spoke on the former minister's resignation amid the scandal, saying it is "very difficult" to see how he could continue as an MSP given the circumstances.

"As for Derek Mackay's own future, that's something that only he can decide," Brown said on BBC Politics Scotland. "It is not something over which the SNP or the Government have any control.

"As things stand Derek Mackay is a suspended member of the SNP and there will be a process through which we will have to go and I think it's better that I don't comment on that just now. "