Conservative candidate Craig Williams has apologised and said he made a “huge error of judgement” over betting on the date of the next general election.

Mr 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 three days before Rishi Sunak announced the 4 July poll.

Speaking to the BBC, he said: “I clearly made a huge error of judgement that’s for sure and I apologise.”

Labour called the allegations “utterly extraordinary”.

Mr Sunak’s decision to call the poll was a surprise to many, including many Conservative MPs, who were expecting an autumn date.

Mr Williams said: “I will not be expanding on my statement because it’s an independent process.

“The gambling commission are looking at it now.”

The former MP, who is standing for the Conservatives in Montgomeryshire & Glyndwr, has been criticised by Lord Cameron, who said it was “clearly a very foolish decision”.

Earlier, the foreign secretary told BBC Breakfast: “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.”

He said Mr Williams was already on the ballot under the Conservative banner, so that couldn’t change, and added Mr Williams “will have to face the consequences of that investigation”.

On Wednesday, Mr Williams had posted on X about the allegations: “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.”

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 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