Dominic Raab is facing multiple formal complaints from Ministry of Justice (MoJ) civil servants over allegations of bullying behaviour during his previous stint running the department, the Guardian has been told. The justice secretary has vowed to “thoroughly rebut and refute” the two official complaints he is already facing, one from the MoJ and one from his time as foreign secretary, but further formal allegations will be a blow to his attempts to clear his name. Downing Street is understood to have appointed an independent figure, expected to be announced on Wednesday, to conduct the inquiry into the deputy prime minister’s alleged behaviour. They will not be limited in the scope of what claims they investigate. A human resources director within the MoJ has been appointed to collate any complaints made by officials before they are handed over to the Cabinet Office, where the investigator, believed to come from outside government and not be a serving civil servant, will be based. MoJ sources claimed that “a handful” of formal complaints had now been made, beyond the initial one from a group of mid-ranking civil servants in the department, who said that Raab oversaw a “perverse culture of fear” that damaged civil servants’ mental and physical wellbeing, while other officials had asked for advice. The new complaints are understood to be from senior civil servants, with direct experience of alleged bullying and aggressive behaviour by the justice secretary when he was previously at the department. “They feel they need to stand shoulder to shoulder with more junior staff,” one source said. One MoJ insider claimed the fresh allegations were “more serious and more specific” than general claims about Raab’s abrasive management style that had been made before. “He was demeaning and aggressive, even to senior staff, and his unpredictability from day to day meant we were all constantly on edge,” they added. It comes after the Guardian reported claims that Raab behaved so badly in a meeting with the Home Office during his first stint as justice secretary that his department’s top official had to personally apologise to counterparts afterwards. Whitehall sources claimed the justice secretary had acted “so badly and inappropriately” at a high-level meeting earlier this year that the MoJ’s permanent secretary, Antonia Romeo, was forced to call senior officials of the then home secretary, Priti Patel, to express regret. Rishi Sunak, who agreed to set up the inquiry into the complaints, has faced questions over his judgment in reappointing Raab to his cabinet after a series of allegations about his behaviour towards civil servants across three different departments, including the MoJ, the Foreign Office and the Brexit department. Angela Rayner, Labour’s deputy leader, said: “The trickle of complaints about Dominic Raab’s conduct is becoming a flood. A week after the first formal complaints were revealed, Rishi Sunak has failed to appoint an independent investigator to examine the slew of allegations about his deputy’s behaviour. “The prime minister’s decision to put party management before the national interest and reappoint a man with Dominic Raab’s track record raises questions about his own judgment and makes a mockery of his pledge to bring integrity, professionalism and accountability to government.” An MoJ spokesperson said: “There is zero tolerance for bullying across the civil service. The deputy prime minister leads a professional department, driving forward major reforms, where civil servants are valued and the level of ambition is high. “There is an independent investigation under way that is being overseen by the Cabinet Office, and it would be inappropriate to comment further on issues relating to it until it is completed”.