Gavin Williamson is facing a complaint that he sent “vile” and “threatening” messages to former chief whip Wendy Morton, raising questions over Rishi Sunak’s decision to reappoint the twice-sacked Tory. Morton is believed to have made a formal complaint to the Conservative party over claims of Williamson’s behaviour to her in the final days of Liz Truss’s government. A source told Tortoise Media that Morton had passed on “vile and threatening messages” she had received during the time she was chief whip, which she considered had a misogynistic undertone. A source close to Williamson, once again a cabinet minister after being appointed by Rishi Sunak, said he “strongly refutes these allegations” and is “very happy to share all communications with the former chief whip with CCHQ [Conservative campaign headquarters] if needed”. The source said he had not been notified by the party of any formal complaint against him. The Conservative party said any complaint would be kept confidential and the whips’ office had no comment. One senior Tory said Morton may have gone to the party with her complaint, rather than the whips, believing that their processes are more robust and can lead to more concrete action. However, Sunak may come under pressure for a more independent investigation into his minister’s conduct in the coming days, such as asking the Cabinet Office’s propriety and ethics team to look into the allegations. Sunak had promised to appoint an independent adviser on ministerial interests but none has been put in place yet. In a previous case the adviser examined claims of bullying by Priti Patel, the then home secretary. Labour says the complaint raises “fresh questions” on Sunak’s judgment in “resurrecting ministers who left government under a cloud of misconduct”. Williamson has been sacked twice. Theresa May forced him to step down as defence secretary after an inquiry into a leak from the national security council, raising security fears, and Boris Johnson ousted him from cabinet over his handling of the exam fiasco when he was education secretary. He entered government after playing a role behind the scenes in getting Sunak elected, after developing a reputation for political persuasion during his time as chief whip. On Sunak’s entry to No 10, Williamson was handed a cabinet job as a Cabinet Office minister without portfolio, roaming across departments. Angela Rayner, Labour’s deputy leader said: “Gavin Williamson was sacked from cabinet twice, yet despite risking national security he has now been put at the heart of the government’s corporate headquarters. “Given his new role and the seriousness of these allegations, there must be an urgent and independent investigation. “Far from restoring integrity, professionalism, and accountability, Rishi Sunak is failing to stop the rot. He promised that appointing an independent ethics adviser would be one of the first things he would do as prime minister, but instead he has given us more of the same old sleaze.” Days before Truss was forced to quit No 10, Morton’s status as chief whip was in the balance amid talk that she had resigned over the fracking vote in the Commons, only for Downing Street to insist she remained in the post hours later. A Conservative party spokesperson said: “The Conservative party has a robust complaints process in place. “This process is rightly a confidential one, so that complainants can come forward in confidence.”