Allies have defended the Home Secretary over accusations she bullied officials after it emerged she sought to remove one of her department's senior mandarins.
Priti Patel looked to move permanent secretary Sir Philip Rutnam from the Home Office after the pair had a series of rows, the PA news agency understands.
The news comes as supporters defended her after it was reported she had been accused of belittling officials, making unreasonable demands and creating an "atmosphere of fear".
According to The Times, Sir Philip has raised concerns with the Cabinet Office about the minister.
But allies of Ms Patel are thought to have regarded the clashes as about nothing out of the ordinary.
A source told PA they "strongly refute" accusations of bullying or belittling and had never seen any evidence of this, instead describing her as "demanding but kind", adding: "But it is a demanding job, that's the nature of the job."
Sir Philip and Ms Patel had "fundamental disagreements about the rule of law", according to a source quoted by the newspaper.
But an ally of Ms Patel told PA they "did not recognise" these claims.
Business minister Nadhim Zahawi rejected the allegations, insisting Ms Patel was "utterly professional" and "works day and night".
The Home Office said no formal complaints had been made against the Cabinet minister.
Matters reportedly came to a head last week when a senior official collapsed after a meeting with Ms Patel following an all-night effort to reverse a High Court ruling barring the deportation of 25 foreign criminals to Jamaica.
At a meeting the following morning he was confronted by the Home Secretary, who demanded to know why the department had failed to reverse the ruling, the newspaper said.
He is understood to have fallen ill later in the day and was taken to hospital, where he was found to have a sodium deficiency, believed to be because he drank too much water while working late.
A source told PA staff were exhausted after working all night but dismissed claims the meeting was heated, instead describing it as "constructive" with officials being asked to work on finding solutions to making sure the situation did not occur again.
Mr Zahawi told LBC: "I've known Priti for 25 years, she's utterly professional, works night and day to deliver for the country and her constituents and is absolutely focused on making sure... the people voted for us to take back control of our borders."
Pushed again on whether Ms Patel is a bully, Mr Zahawi said: "No, I don't think she is at all.
"I've worked with Priti in the past on several campaigns, I've known her literally for 25 years, she is a brilliant, collegiate team player."
But Dave Penman, general secretary of the FDA union which represents senior civil servants, said staff at the Home Office were "working flat out" and warned that ministers must recognise the consequences of their behaviour.
He said: "The Home Office, by its very nature, has a wide-reaching, demanding policy agenda, and civil servants working in the department are used to rising to these challenges.
"Members in the Home Office are already working flat out, with our latest survey finding 70% within the department felt the working of excess hours is a problem, with the same amount stating they had worked whilst on sick leave in the last year.
"Putting undue pressure and demands on committed public servants that are already overstretched does not make for good government and will do this administration no favours in delivering its policy priorities.
"Ministers have to recognise the consequences of their behaviour. An 'atmosphere of fear' is obviously not conducive to a successful workplace and anonymous briefings against civil servants who cannot answer back are not only unfair to the individual, they corrode public trust in government."
A Home Office spokesman said: "We have not received any formal complaints and we take the welfare of our staff extremely seriously."
An ally of Ms Patel told The Times: "The Home Office is dysfunctional and the current permanent secretary had presided over a sacking of a home secretary (Amber Rudd) and accidental deportations.
"If this were any other environment Philip Rutnam would not only be sacked he'd be denied a pension."