Suella Braverman is facing fresh controversy after it was claimed civil servants in her department were forced to “fact-check” the home secretary’s statements to cabinet on up to six occasions. Concerns have been raised about the under-fire minister’s competence, as Downing Street denied Rishi Sunak was dithering about whether to launch an investigation into a potential breach of the ministerial code over her bid to avoid a speeding fine. Government sources told the Guardian Braverman has repeatedly got things wrong, including during cabinet talks about King Charles’s coronation in March and in meetings held this week on migration, in which she overstated the number of Ukrainians and Hongkongers who had come to the UK by tens of thousands. One insider said she made “basic errors”, while another said she “keeps getting facts wrong”. After meetings with other senior ministers, the Cabinet Office was said to have had to contact officials from the Home Office, who were asked to “factcheck” her claims. There was no such similar problem when her predecessor, Priti Patel, ran the Home Office, the Guardian was told. A source close to Braverman disputed the suggestions and claimed they had no awareness of such issues. Sunak has not yet decided whether to ask his ethics adviser to look into Braverman’s attempt to arrange a private speed awareness course and concerns about her attempt to draw on civil servants to help her. He has asked her for “further information”, according to the Cabinet Office minister Jeremy Quin, who fielded questions in the Commons on Tuesday. Despite no firm decision having been publicly announced, No 10 insiders suggested that Braverman could be in the clear because they felt there had not been enough of a public outcry for her to face a severe sanction. Tory MPs are in a “mutinous” mood, with government frontbenchers understood to have spoken to figures in the whips’ office to voice their frustration with a lack of action being taken against Braverman. Braverman’s special adviser, who is accused of having told a journalist who asked whether she had been caught speeding that it was “nonsense” before the story became public, is also coming under scrutiny. Sunak’s spokesperson confirmed they were being looked at “in the round”. Some Whitehall experts and former civil servants have downplayed a potential breach of the rules by Baverman. Gus O’Donnell, a former head of the civil service, told an event at the Institute for Government on Tuesday morning: “One of the things that was wrong about the ministerial code [is] that people thought, journalists in particular, about this, ‘A-ha, gotcha! You broke the ministerial code, therefore you must resign’, which is not true. “It shouldn’t be true. It should be, ‘You broke the ministerial code, it is actually a relatively minor offence, I am going to give you a yellow card and we’ll move on’.” Jill Rutter, a former No 10 civil servant and government expert at UK in a Changing Europe and the Institute for Government, also said it might fall into the category of a bad judgment for which she is in “final, final warning territory”. She said the context and tone of the incident was important, including how strongly she had asked civil servants to look into a private course. “Should she have asked? Probably not. That’s bad judgment and an inappropriate thing to do. But if people said they couldn’t help her, and in terms of ordering the civil service around, it looks as if she desisted. If she was just inquiring whether this was possible, it is different from saying: ‘Look, I’m the home secretary, don’t you know who I am?’ It’s all bad, but Sunak will have to decide: is it worth sacking her over?” She said in a more functioning system the ethics adviser, Sir Laurie Magnus, would be able to order his own investigation rather than relying on Sunak as the person to trigger an inquiry. Braverman has defenders within politics, particularly on the Eurosceptic right of the party. One political aide who has worked with Braverman said she was steely and extremely clever, as well as persistently underestimated by her colleagues. They said she was still very well-regarded by the European Research Group wing of the party and Sunak would not be strong enough to move against her, even if he wanted to.