Lord Cameron has said it was “clearly a very foolish decision” by a fellow Conservative for reportedly gambling on the date of the next general election.

Craig Williams, who was an aide to the prime minister in the last Parliament, is alleged to have placed a £100 bet on a July election a few days before Rishi Sunak announced the 4 July poll.

Mr Williams, who is standing for the Conservatives in Montgomeryshire & Glyndwr, posted on X saying that the Gambling Commission is making “routine inquiries” after he placed “a flutter” and that he is cooperating with that inquiry.

Labour called the allegations “utterly extraordinary”.

Asked by BBC Breakfast, Lord Cameron said: “His situation, having made this clearly very foolish decision, is he is being investigated by the Gambling Commission – and they have considerable powers in terms of what the consequences could be.

“I think we have to let the investigation take place and so I can’t really comment further on it.”

The foreign secretary and former PM said Mr Williams was already on the ballot under the Conservative banner, so that couldn’t change.

He added Mr Williams “will have to face the consequences of that investigation”.

Mr Williams’ post said: “I’ve been contacted by a journalist about Gambling Commission inquiries into one of my accounts and thought it best to be totally transparent.

“I put a flutter on the general election some weeks ago. This has resulted in some routine inquiries and I confirm I will fully cooperate with these.

“I don’t want to be a distraction from the campaign, I should have thought through how it looked.”

According to the Guardian, Mr Williams placed his bet three days before Mr Sunak named 4 July as the date, with a potential £500 payout.

Conservative Wales Office minister Fay Jones confirmed the Gambling Commission had “spoken to” Mr Williams and said “they are making some preliminary investigations”.

She told BBC Wales Live: “It’s not great, there’s no two ways about that… Let’s get the facts first, before we make a decision.”

Political opponents reacted sharply, with Welsh Labour’s Stephen Kinnock labelling the situation “utterly extraordinary”.

He added: “It’s really important that the Gambling Commission acts quickly, and they come back with a clear verdict on what Mr Williams has done.”

Plaid Cymru’s Westminster leader Liz Saville Roberts told the programme: “It begs the questions of what Mr Williams’ judgement was in relation to putting a date on what we presume to be the general election.”

A Gambling Commission spokesperson said it does not “confirm or deny whether any investigations are underway unless or until they are concluded, or if arrests are made or charges are brought during a criminal investigation”.

The spokesperson also said that the confidential use of information in order to gain an unfair advantage when betting “may constitute an offence of cheating under Section 42 of the Gambling Act, which is a criminal offence”.

The BBC has contacted Mr Williams for comment.

The other candidates standing in Montgomeryshire and Glyndwr are:

• Jeremy Brignell-Thorp, the Green Party
• Oliver Lewis, Reform UK
• Glyn Preston, Liberal Democrat
• Elwyn Vaughan, Plaid Cymru
• Steve Witherden, Labour