Nicola Sturgeon and Barrhead's MP Kirsten Oswald have been accused of a failure of leadership over the Derek Mackay scandal.

Eastwood MSP and interim Scottish Conservative leader Jackson Carlaw hit out after there were further revelations over Mr Mackay's messages to a 16-year-old boy.

It emerged the Scottish Government demanded to know the "justification for publication" of the story which exposed him and also wanted the name of the teenager he is accused of sending hundreds of messages to.

Opposition politicians hit out at the "predatory" behaviour of Mr Mackay, who had been tipped as a future successor to Ms Sturgeon.

Mr Carlaw claims there has been a "collective failure of leadership" from the First Minister and SNP business convener Ms Oswald after the story emerged.

A separate report in the Daily Record said SNP activist Shaun Cameron, 25, had been sent dozens of unwanted messages by Mr Mackay over a period of four years.

He claimed the MSP contacted him on Facebook after meeting him at an SNP event when he was 21, adding that some of the messages were "quite suggestive."

Mr Cameron said one message sent by Mr Mackay in September 2017 read: "Got any naughty pics?"

Commenting on the latest developments, Mr Carlaw said: "Nicola Sturgeon, when asked yesterday in the Scottish Parliament if she had sought assurances from Derek Mackay that the story reported was an isolated incident, replied merely that she was unaware of any other potential victims.

"It is now clear that no such assurances were sought from Mr Mackay by the First Minister, given there are other people coming forward.

"From the start, it seems the SNP Government has been more interested in protecting its own reputation than in the welfare of potential and actual victims."

Read more: Carlaw: Disgraced MSP Mackay's conduct 'could be damaging to Parliament'

Mr Carlaw said the Scottish Government and the SNP "should have already established a confidential hotline for potential victims to contact to report concerns and to receive appropriate support".

He added that Ms Sturgeon and Ms Oswald "both now need to respond and act with far greater urgency and understanding".

A spokesman for the SNP said: "Once the First Minister became aware of the allegations on Wednesday evening, decisive action was taken and Derek Mackay resigned.

"He was suspended from the SNP as soon as the full details, which we had asked for the previous evening, were published by The Sun on Thursday morning.

“The SNP has established procedures for individuals to raise concerns about members, including the option of doing that independently and anonymously if they wish.”

Scotland's Deputy First Minister John Swinney, who said he was "utterly stunned" by the revelations, insisted the government had "simply asked for information to give us the veracity and the substance of the points that were being put to us".

He told BBC Radio Scotland that, when he was informed the story was going to be published, it was "the first time that I had heard any revelations of this type".

Mr Mackay, the MSP for Renfrewshire North and West, quit as finance secretary on Thursday morning, just hours before he had been due to deliver the Scottish Budget to Holyrood.

His resignation came after The Scottish Sun reported he had sent 270 messages to the boy he befriended on Facebook and Instagram.

Mr Mackay is reported to have called the youngster "cute," as well as offering to take him to a rugby game and out to dinner.

The politician came out as gay in 2013 and accepted in his resignation statement that he had "behaved foolishly".

He apologised unreservedly to the teenage boy and his family.

Mr Mackay said: "I take full responsibility for my actions. I have behaved foolishly and I am truly sorry."

Speaking at Holyrood on Thursday, Ms Sturgeon said: "Derek Mackay has apologised unreservedly for his conduct and recognised, as I do, that it was unacceptable and falls seriously below the standard required of a minister."