Dominic Raab has been nicknamed “The Incinerator” because he “burns through” staff so quickly, it can be revealed.
Officials working for the Deputy Prime Minister have accused him of creating a “climate of fear” in the Ministry of Justice.
Mr Raab was ousted from the department when Liz Truss became PM, but he returned just seven weeks later when Rishi Sunak entered No10 last month.
Government sources said concerns have been raised about the turnover of staff in roles working closely with the minister.
“He is known as The Incinerator as he burns through officials,’ one told the Mirror. “The mood is grim in his office.
“People are desperate to escape the climate of fear as quickly as they can.”
Around half of the staff working in Mr Raab’s private office are understood to have requested to move when it was announced he was returning. Civil servants became “emotional” on hearing he was coming back.
Mr Raab was appointed Justice Secretary last September following his botched handling of the Afghanistan crisis at the Foreign Office.
Ministry of Justice sources confirmed Antonia Romeo, the department’s permanent secretary, had spoken to Mr Raab about his treatment of staff on his return last month.
Opposition politicians have demanded an investigation into his behaviour. Labour deputy leader Angela Rayner said: “Rishi Sunak claimed zero tolerance for bullying, promised a government of integrity and pledged to urgently appoint an ethics adviser, yet is falling far short on every promise.
“Rishi Sunak is already showing he is not just failing to stop the rot but letting it fester."
Liberal Democrat deputy leader Daisy Cooper said the claims against Mr Raab “are deeply disturbing and must be investigated immediately by the Cabinet Office”.
"This Government hasn't got a shred of integrity left - every day more chaos, sleaze and scandal is unearthed,’ she added.
" Dominic Raab now joins a long list of Conservative ministers to have allegations made against them for inappropriate behaviour.
"These latest reports cannot be brushed under the carpet by Rishi Sunak. He must launch an investigation into [Mr] Raab with immediate effect.
"No staff, whether in the civil service or any other sector, should be subjected to working with or for a bully."
A source close to Mr Raab last night insisted there had not been a “high turnover of staff” working for him.
“His private office are very good and dedicated, and we are pleased to enjoy long term working relationships with them,” they said.
A Ministry of Justice spokesman 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.”
In his first speech as Prime Minister, Mr Sunak pledged: “This government will have integrity, professionalism and accountability at every level.”
The PM’s secretary insisted he has “zero tolerance” for bullying after Gavin Williamson was forced to resign from Cabinet earlier this week.