The UK Gambling Commission has reportedly asked operators to share all bets worth £20 or more on the upcoming general election, as Nick Mason became the fourth Conservative named as part of the regulator’s investigation.

The controversy over politicians betting on a July election has continued to deepen since parliamentary hopeful Craig Williams became the first person confirmed in the probe earlier this month.

Nick Mason, the Tories’ chief data officer, was named by The Sunday Times as the fourth Conservative involved in the probe.

Meanwhile, BBC News reports that the Gambling Commission has asked betting companies to disclose all bets worth £20 or more on the date of the election.

The regulator’s probe involves more people than those publicly named, it adds. A Metropolitan police officer in Rishi Sunak’s protection team, who has not been named, is also part of the probe.

Laura Saunders, who is standing for the Bristol North West seat on July 4, was the second Tory to be named, followed by her husband Tony Lee, the Conservatives’ director of campaigning.

As for Mason’s involvement, The Sunday Times said he allegedly placed “small” bets less than £100 but would have won “thousands” of pounds.

Gambling Commission rules state that using confidential information to gain an unfair advantage when betting could constitute a criminal offence.

Mason has now taken a leave of absence, as has Lee, and a spokesperson for the former denied wrongdoing.

Prime Minister Rishi Sunak last week promised to “boot out” any members of his party found to have breached gambling laws.