NICOLA Sturgeon has been accused of "gagging" her own MSPs in an attempt to maintain the appearance of party unity over Brexit.

Two nationalist MSPs said yesterday that they had been told to refer media enquiries to party officials after former SNP minister Alex Neil admitted that he and other Holyrood colleagues had secretly voted Leave.

Meanwhile, Angus MacNeil, one of Ms Sturgeon's most senior MPs and the chair of Westminster's International Trade Committee which will have a vital role as Brexit approaches, refused to confirm how he had voted in the EU referendum leading to speculation that he had also backed withdrawal.

Contacted by The Herald and asked whether he was willing to say how he voted, he replied: "No, not really, no... I don't think I'm going to say anything." Pushed over whether he would reveal if he voted Leave or Remain, he said: "I'm not going to say anything at the moment."

Mr Neil revealed that he had decided to vote for Brexit 10 days before June's referendum, but had previously kept quiet out of loyalty to his party.

The Airdrie and Shotts MSP, who held three cabinet posts under both Alex Salmond and Ms Sturgeon but left the cabinet following the SNP's election victory in May, said that "one or two" of his Holyrood colleagues had approached him to say they had also backed Brexit.

The First Minister said it was no surprise that Mr Neil had voted to leave the EU that she was "not sure he's right about other MSPs".

However, members of Ms Sturgeon Holyrood group revealed that they had been told to keep quiet.

One SNP MSP said: "I'm happy to say that I voted Remain and I'm genuinely enthusiastic and always have been about Europe. But the party is telling us not to speak to the press about it but to refer everything back to the centre. I suppose they're worried because some of us will tell you that we definitely voted to Remain so you could probably assume the others voted to Leave."

A second MSP said they received an email yesterday morning from the party alerting them to a story about Mr Neil, and advising them to direct all press queries to SNP HQ.

The MSP, who also voted Remain, said: "It was an email reminding us that all national press questions had to go to central office. It said all members would probably get some communication from national newspapers regarding the Alex Neil story."

The MSP said the tactic was not unusual, but disagreed with it in this case.

"I would have said, 'Just tell people how you voted and let people do it on the record.' They’re scared that someone says, 'Yes, I voted for Brexit. Alex Neil is right.'"

Opposition parties said that SNP MSPs who voted Leave should come clean with their constituents and that revelations that SNP politicians had voted for Brexit undermined Ms Sturgeon's talk of a second independence referendum to preserve EU status.

The row follows the SNP conference, when a minority of members openly questioned the First Minister's strategy.

Adam Tomkins, the Tory constitution spokesman, said: "Nicola Sturgeon’s façade of unity on this issue is peeling away. She’s so worried another MSP will break ranks she’s set down a gagging order instead.

"That’s not good enough. We already know more SNP supporters voted to Leave than any other party in Scotland. It’s time the MSPs told the truth on this matter."

Lewis Macdonald, Labour's Europe spokesman, said: "It strikes many Scots as odd for the SNP to be in favour of one political union but not the other, so at least Alex Neil is consistent."

An SNP spokesman said: "Press officers routinely offer advice to members."