NICOLA Sturgeon banned disgraced former finance secretary Derek Mackay from going out drinking during conferences due to concerns over his behaviour, it has been claimed.

After a day of revelations which forced Mackay to resign, a former senior SNP staff member told The Herald it was “common knowledge” that Mackay was openly flirtatious with younger male members of the party.

READ MORE: Derek Mackay: Former finance secretary faces fresh allegations over unwanted messages

Camley's Cartoon: Derek Mackay resigns.

The 42-year-old is also said to have regularly enjoyed energetic evenings at nightclubs with young men.

Mackay was claimed to have been highly enthusiastic at the party’s infamous “conference karaoke” social events, which take place each year.

Eventually the First Minister advised the MSP not to go out partying after his behaviour came up at senior staff meetings, the ex-staff member said.

Mr Mackay, who was suspended from the party yesterday, even joked at the 2017 party conference that attendees would not be seeing him at the pub after the event as “Nicola won’t let me”.

He resigned yesterday after bombarding a schoolboy he befriended on Facebook and Instagram with hundreds of online messages over a six-month period – including one calling him “really cute”.

READ MORE: From rising star to resignation: the downfall of Derek Mackay

The messages, which were published in the Scottish Sun and sent shockwaves through Holyrood, continued even after the boy revealed he was still in school, and then later said he was 16.

Scottish Conservative interim leader Jackson Carlaw said Mr Mackay’s “grooming-style behaviour is completely disgraceful” and said it was hard to see how he can continue as an MSP.

Scottish Labour leader Richard Leonard said Mr Mackay’s actions were “predatory and must be thoroughly investigated”, adding: “He has abused his position of power with a vulnerable adolescent.”

Police Scotland said it had not received any complaint of criminality, but added: “We are currently assessing available information from media reporting and would encourage anyone with information to please come forward.”

Mr Mackay resigned as finance secretary on Wednesday night, on the eve of the £40 billion draft Scottish Budget. Ms Sturgeon told MSPs he had also been suspended “pending further investigation”.

Mr Mackay, a father-of-two who came out as gay in 2013, was once tipped as a future First Minister. But Ms Sturgeon said his behaviour fell “seriously below” the standards required of a minister. She also said there are “clearly” issues for Mr Mackay to reflect on in terms of whether he continues as an MSP.

Mr Mackay accepted he had “behaved foolishly” as he apologised unreservedly to the boy and his family.

In one message, he asked the teenager: “And our chats are between us?” When the boy agreed, Mr Mackay told him: “Cool, then to be honest I think you are really cute.”