The prime minister ducked the question as Jeremy Corbyn condemned what he suggested appeared to be “a shocking and unacceptable pattern of behaviour” by the beleaguered home secretary.
Sitting alongside Ms Patel, the prime minister instead offered her his staunch support, insisting she was “doing an outstanding job” and adding: “I am sticking by her.”
The Labour leader seized on the revelation that Ms Patel has been accused of bullying staff at a third government department.
“On each occasion, tens of thousands of pounds of hard-earned taxpayers’ money has been spaffed up the wall to buy their silence,” Mr Corbyn alleged.
“Was the prime minister aware of these allegations and, if he was, why did he appoint her?”
Mr Johnson swerved the question, saying: “The home secretary is doing an outstanding job.
“If there are allegations, of course it is right that they should be properly investigated by the Cabinet Office and that is what has happened.”
Later, the prime minister declined to say whether Ms Patel would be “expected to resign” if the inquiry – led by the cabinet secretary, Mark Sedwill – finds that she has breached the ministerial code of conduct.
Instead, he said he would “take no lessons” from a Labour Party stained by the driving out of several MPs in the antisemitism scandal, while insisting that he “loathed” bullying.
The dangers for Mr Johnson are rising, as the inquiry he has ordered will examine all complaints made against Ms Patel in her various jobs.
Furthermore, the staff who have attacked her behaviour at the Department for International Development are reported to be ready to give evidence at Philip Rutnam’s tribunal hearing.
One cabinet minister told the BBC’s Newsnight programme that the situation threatened to turn into “Armageddon” for the prime minister – who may himself be required to give evidence.
Significantly, Mr Johnson stationed the home secretary alongside him on the Commons front bench and said: "She is keeping this country safe ... She is bringing in a system to tackle our migration crisis.”
Following the exchange in parliament, Labour said civil servants from the Home Office and other departments had approached Mr Corbyn’s office over the past 24 hours with new bullying allegations.
“These relate to Priti Patel and another former minister,” the Labour leader’s spokesperson said. “These are bullying and harassment allegations from government staff.
“They simply build up the picture that has already accumulated over recent days,” they said, while declining to reveal the details.
Earlier, a Home Office spokesperson said: “The home secretary categorically rejects all of these allegations.”
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