Rishi Sunak does not disclose whether his adviser knew the election date

The Prime Minister refused to say whether he had told his parliamentary adviser Craig Williams the date of the general election.

The Conservatives withdrew their support for Mr Williams as a candidate on Tuesday after he admitted betting on the election date. He denied committing any offence.

The Metropolitan Police had previously announced that the number of officers being investigated for betting on the timing of the election had risen from six to at least seven.

A member of the royal family and a specialist bodyguard arrested on suspicion of abuse of office remain free on bail and are only able to carry out their duties to a limited extent. Six other officials have been identified who placed bets on the timing, the Met said.

The head of the Gambling Commission, which is conducting an investigation with the Met, said they would not confirm the names of the suspects to “protect the integrity of the investigation”.

Faced with repeated questions about Mr Williams during a campaign visit to Derbyshire, Mr Sunak insisted it would not be right for him to say more about the ongoing investigation.

He said he was furious when he learned of the allegations and made it clear that anyone who violated the rules would be punished to the full extent of the law.

Mr Sunak told reporters he was not aware of any investigations into election candidates or Conservative officeholders other than those already publicly known.

Separately, it was reported that a senior Conservative had bet £8,000 that he would lose his seat.

Sir Philip Davies has neither confirmed nor denied the bet, which was first reported by The Sun, but denied having done “anything illegal”.