Pat McFadden, Labour’s campaign co-ordinator, called on Mr Sunak to withdraw support from the two Conservative candidates over the allegations.

In a letter to the Prime Minister, he wrote: “Can I ask you very simply why you think that a serving police officer should be suspended from his role because of allegations that he made a bet based on inside information, while the two colleagues of yours who so far stand accused of the same offence – Craig Williams, your PPS parliamentary private secretary, and Laura Saunders, a member of your Conservative Campaign Headquarters staff and partner of your campaigns director – are still being allowed to stand as Tory candidates in the election on July 4?

“Surely you can understand that – yet again – this looks as though there is one rule for members of the Tory party and another rule for everyone else, specifically on this occasion a serving police officer. If you can see how wrong that is, will you now at the very least remove your support for Mr Williams and Ms Saunders as Conservative election candidates?”

Speaking on the Tory campaign battle bus in London, Michael Gove told broadcasters: “Obviously, it doesn’t look great, and obviously the conclusions lots of people are drawing are not at all great. But I don’t know all the facts at the moment. I’d be loath to condemn without there being an investigation that’s been concluded.

Asked whether whips or the Conservative Party had warned campaigners not to engage in gambling behaviour linked with an election, the Levelling Up Secretary said: “I would hope you wouldn’t need to be told. 

“Obviously if, as a private individual, I put a bet on the Grand National or on the Euros, that’s one thing – but using privileged inside information is wrong.”

Asked for comment, a Tory spokesman repeated the statement from Wednesday night.