The Department of Health has not received any formal complaints about the behaviour of Health Secretary Steve Barclay, a spokesman has said.
The statement comes in response to a Guardian report that civil servants “raised concern” about his conduct.
Sources told the paper officials had informally complained to the top civil servant in the department about the way Mr Barclay had treated colleagues.
A source close to the health secretary said the allegations were “untrue”.
Foreign Secretary James Cleverly told Sky News that his colleague Mr Barclay was “absolutely not” a bully.
Asked about the Guardian story, a Downing Street spokesman said: “Ministers should be able to test and challenge civil servants and their political advisers robustly, and hold departments to account to deliver for the public.”
Mr Barclay became MP for North East Cambridgeshire in 2010 and has since served in a number of government roles including Brexit secretary and chief secretary to the Treasury.
The Guardian quoted one source describing Mr Barclay as “constantly angry”, while a separate source said: “He hauls people over the coals and is generally a bit unpleasant.”
However, someone who has worked with him told the BBC the claims were “totally unsubstantiated and a politically motivated attack”.
Another government official said many colleagues “speak highly” of Mr Barclay and are unhappy about the briefings.
The report comes at a difficult time in the relationship between civil servants and ministers.
Last week, Dominic Raab – a senior minister and close ally of the prime minister – resigned after a bullying inquiry found he had acted in an “aggressive” way towards civil servants.
In his resignation letter, Mr Raab said he felt “duty bound” to accept the outcome but later launched an attack on “activist civil servants” who he claimed had tried to block reforms they didn’t agree with.
He told the BBC the inquiry’s findings set “a very dangerous precedent” adding: “If the bar, the threshold for bullying is lowered that low, it’s almost impossible for ministers to deliver for the British people and I think it’ll have a chilling effect on effective government.”
Dave Penman, general secretary of the FDA union, told the BBC: “Some of the complainants have said to me their experience and in particular how the PM handled it means they would not advise people to complain.
“All this nonsense about the bar being lowered is quite the opposite.”
However, others have told the BBC they think more complaints will be made.
Asked about the reports in the Guardian about Mr Barclay’s alleged behaviour, a Department of Health spokesperson said: “The department has not received any formal complaints relating to the behaviour of its ministers.
“Any complaints, relating to ministers or members of staff, would be investigated in line with departmental guidance.”
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