Concerns over Dominic Raab’s behaviour towards officials were raised inside Whitehall during his time as Brexit secretary in 2018, the Observer has been told. In the latest allegation against Raab over his conduct in government, a senior source said that a document outlining a “formal expression of concern” was dispatched to the Cabinet Office by a prominent official in the Brexit department. It is understood that the document alleged “unprofessional, even bullying, conduct of the minister towards his private office”. A source with knowledge of the complaint said that no action was taken. Raab served as Brexit secretary only briefly between July and November 2018. The cabinet office said that it had not received a formal complaint. However, it is not clear whether the document submitted was intended to represent a formal complaint. The revelations, also reported by ITV News, come after the Guardian revealed civil servants at the Ministry of Justice were offered “respite or a route out” of the department when Raab was reappointed last month. Some were said to have concerns about his previous behaviour there. About 15 members of staff are said to have been taken into a room where departmental officials acknowledged they might be anxious about his past behaviour and gave them the option to move to different positions. However, sources close to Raab have said that while he expects high standards from officials, he is “always professional and clear with them”. Antonia Romeo, the MoJ’s permanent secretary, is understood to have spoken to Raab when he returned to the department under Rishi Sunak’s leadership. She is said to have told him to treat staff with respect. Raab was brought back as justice secretary following his prominent role in Sunak’s leadership campaign. Sunak also handed him the title of deputy prime minister. The claims about Raab follow the departure of Gavin Williamson from cabinet after complaints of alleged bullying of colleagues. It is alleged he sent expletive-laden messages to former chief whip Wendy Morton complaining about not being invited to the Queen’s funeral. There were also allegations against him from civil servants during his time as defence secretary. A source aware of the claims made about Raab during his time as Brexit secretary was critical of the cabinet office’s response, stating it was “useless and unreliable” in protecting civil servants. “As usual nothing happened,” they said. “It wasn’t the first time that civil servants have expressed concern to the cabinet office and nothing has been done.” Another senior official who had experience working with Raab said that he had not been aggressive, but was obsessed with minor details and insisted on documents being formatted in a specific way, while refusing to take home ministerial red boxes after Thursday evening. “Working with him was not for the faint-hearted,” they said. “He could be very hard work.” There is now debate among Tories about the way in which Raab conducts himself. One former minister said: “Everyone dreaded him coming back to the MoJ. He is utterly unreasonable, and only works through Spads. He was utterly undiplomatic.” However, Helen Grant, who worked with him as a minister at the Foreign Office, said Raab had been “very decent”, with “high professional standards”. The MoJ 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.” Opposition parties have been calling for a formal investigation of Raab. “These latest reports cannot be brushed under the carpet by Rishi Sunak. He must launch an investigation into Raab with immediate effect,” said Lib Dem Daisy Cooper. “No staff, whether in the civil service or any other sector, should be subjected to working with or for a bully.” A spokesperson for Raab said: “Dominic has never received nor been made aware of any formal complaint against him. He consistently holds himself to the highest standards of professionalism and enjoys good working relationships with officials across Whitehall.”