A Conservative politician has become the fifth party figure to be investigated by the gambling watchdog for allegedly placing a suspicious bet on the general election date, as the developing scandal continued to overshadow Rishi Sunak’s campaign. The Gambling Commission has informed Russell George, a Tory member of the Welsh parliament who represents the same constituency as Sunak’s closest parliamentary aide Craig Williams, that he is part of its inquiry. The disclosure came after the Tories finally dropped the two Westminster candidates, including Williams, who are under investigation for allegedly placing bets on a July election, after previously standing by them. That U-turn came as the Met has also confirmed that five more police officers have been identified by the watchdog – a week after it announced that a protection officer guarding the prime minister had been arrested for allegedly placing a bet. In a separate development, Labour was also drawn into the gambling row for the first time as the party announced it was suspending the Central Suffolk and North Ipswich candidate Kevin Craig after the Gambling Commission launched an investigation. Craig, a lobbyist and expert in political crisis management, confirmed that he was under investigation for betting that he would not win his own constituency. Labour said it would now return £100,000 he had donated to the party under Keir Starmer’s leadership, while the shadow health secretary, Wes Streeting, would give back £13,000 donated for staffing costs. Marsha de Cordova, another Labour candidate, also said she would give back £2,436 Craig donated earlier this year. A Labour spokesperson said: “With Keir Starmer as leader, the Labour party upholds the highest standards for our parliamentary candidates, as the public rightly expects from any party hoping to serve, which is why we have acted immediately in this case.” In a statement, Craig said: “Throughout my life I have enjoyed the odd bet for fun whether on politics or horses. A few weeks ago when I thought I would never win this seat I put a bet on the Tories to win here with the intention of giving any winnings to local charities. “While I did not place this bet with any prior knowledge of the outcome, this was a huge mistake, for which I apologise unreservedly.” He added: “It is right that the party upholds the highest standards for its parliamentary candidates – just as the public expects the highest standards from any party hoping to serve in government. I deeply regret what I have done and will take the consequences of this stupid error of judgment on the chin.” George, a Senedd member, is the latest Tory figure to be facing an investigation in a growing gambling affair that has engulfed the party during the election campaign and has led to at least two party officials taking leave of absence from headquarters. He represents Montgomeryshire in the Welsh parliament, covering the same area that Williams represented at Westminster. He will step back from his role as the Welsh Tories’ deputy chief whip until the investigation has concluded. In a statement to the Guardian, he said: “Whilst I will cooperate fully with the Gambling Commission, it would not be appropriate to comment on this independent and confidential process. “Doing so would only jeopardise and undermine the investigation. It is the Gambling Commission, not the media, that has the responsibility, powers and resources to properly investigate these matters and determine what, if any, action should be taken. “I have stepped back from the shadow cabinet while the investigation is ongoing. I have done this as I do not wish to be an unnecessary distraction to their work.” Andrew RT Davies, leader of the Welsh Conservatives, said: “Russell George has informed me that he has received a letter from the Gambling Commission regarding bets on the timing of the general election. “Russell George has stepped back from the Welsh Conservative shadow cabinet while these investigations are ongoing. “All other members of the Welsh Conservative Group have confirmed that they have not placed any bets. “I will not issue further comment on this ongoing process, recognising the Gambling Commission’s instruction for confidentiality to protect the integrity of the process.” Alister Jack, the Scottish secretary, revealed on Tuesday evening that he had placed three bets on the date of the general election, one of which was successful, but said that he wanted to make “absolutely clear I have not breached any gambling rules”. “I had no knowledge of the date of the election until the day it was called. As I have said previously, I placed no bets in May and am not under investigation by the Gambling Commission,” he said. The Guardian first uncovered the gambling scandal by revealing two weeks ago that Craig Williams was the subject of an investigation by the watchdog for betting that the election would be in July, three days before it was called. The watchdog is also examining bets allegedly placed by Tony Lee, the Conservative party’s campaigns director and his wife, Laura Saunders, the Tory candidate in Bristol North West, as well as Nick Mason, the Tories’ chief data officer. The decision to drop Williams and Saunders on Tuesday is Sunak’s latest effort to draw a line under the gambling scandal that has dogged his election campaign for two weeks. The party said on Tuesday that it could no longer support the candidacy of Williams, who is standing in Montgomeryshire and Glyndŵr, and Saunders, meaning their campaigns will no longer be supported and they would not have the Conservative whip if they won the seats. However, the pair are believed not to have had their membership of the party suspended while the Gambling Commission inquiry is continuing. A party spokesperson said: “As a result of ongoing internal inquiries, we have concluded that we can no longer support Craig Williams or Laura Saunders as parliamentary candidates at the forthcoming general election. “We have checked with the Gambling Commission that this decision does not compromise the investigation that they are conducting, which is rightly independent and ongoing.” The Guardian has learned that the first Met officer identified as facing election gambling allegations that surfaced last week, is being investigated for placing multiple bets, some of which involved a stake of more than £100. The police constable, who was serving as a close protection officer guarding the prime minister, faces allegations that two bets at least were placed in betting shops with more placed via online gambling sites, making five in total. The officer has a distinctive name, with the bets being placed in the formal version of his name, which is the same as that of a prominent Conservative politician. The officer is being investigated for the offence of misconduct in public office and placed on restricted duties by the Met. The investigation into five further Met officers has not seen them suspended or placed on restricted duties, the Met confirmed. Investigators will examine whether there were any links between these five and the Met officer identified last week. A spokesperson for the Gambling Commission said: “The Gambling Commission regulates gambling in the interests of consumers and the wider public. “Currently the commission is investigating the possibility of offences concerning the date of the election. This is an ongoing investigation, and the commission cannot provide any further details at this time. “We are not confirming or denying the identity of any individuals involved in this investigation.”