Mr Jack is not a candidate for the Tories at the election and is no longer an MP in Dumfries and Galloway because Parliament has been dissolved for the election.  

However, ministers continue to serve in their posts during an election period, meaning that he could potentially be sacked by Mr Sunak from his Cabinet post.

The SNP said Mr Jack had a “duty to come forward with the full details”, with the party’s Scotland spokesman Tommy Sheppard saying: “As a senior cabinet member in the Tory government, and a well-known confidant of Sunak, Jack is obviously in the loop when it comes to Conservative Party planning.

“Alister Jack has a duty to come forward with the full details of precisely what bets he placed on the election and when the public deserve answers immediately.”

When approached for comment, the Tories pointed to Mr Jack’s statement, but the Prime Minister will face pressure to act quickly following criticism of how long it took to suspend Tories accused of being involved in the gambling scandal.

On Tuesday night it emerged that Mr George, a member of the Welsh Assembly, is the fifth Tory being looked at by the Gambling Commission.

In the Senedd he represents Montgomeryshire – the same area served by Craig Williams, the Conservative MP who has admitted betting on the election.

Welsh Tory ‘steps back’

Andrew RT Davies, the Welsh Tory leader, confirmed that Mr George was under investigation and had “stepped back” from his role as deputy chief whip.

“All other members of the Welsh Conservative Group have confirmed that they have not placed any bets,” he said in a statement.

His announcement came after the Conservatives suspended two MP candidates over allegations that they placed bets on the date of the snap election.

The party withdrew support for Mr Williams and Laura Saunders following an internal inquiry into their actions.

Ms Saunders is married to Tony Lee, the Tory party’s director of campaigning, who is also being investigated, as is Nick Mason, its head of data.