In footage released by ITV News filmed as the camera repositioned for extra shots, Ms Keegan – still wearing her microphone – criticised others and claimed the Government had gone “over and above” in addressing concerns relating to reinforced autoclaved aerated concrete (Raac).
She said: “Does anyone ever say, you know what, you’ve done a f****** good job because everyone else has sat on their arse and done nothing?
“No signs of that, no?”
Ms Keegan later apologised, telling broadcasters it was an "off-the-cuff remark after the news interview had finished, or apparently after it finished".
"I would like to apologise for my choice language, that was unnecessary," she said.
Education secretary Gillian Keegan is recorded on camera saying others ‘have been sat on their a***s’ on schools Raac crisis and shares frustration about not being thanked for doing ‘a f***ing good job’https://t.co/c02gI4dXiM pic.twitter.com/jWbYTVZl5D
— ITV News Politics (@ITVNewsPolitics) September 4, 2023
The Education Secretary took part in a series of broadcast interviews on Monday morning about the decision to fully or partially close schools in England because of safety concerns about Raac.
The minister's comments came at the conclusion of an interview with ITV's Daniel Hewitt in which she said he had been "pressing me quite hard" and claimed he was "making out it was all my fault".
In her apology, the Education Secretary refused to say who she believed was "sat on their a**e".
Ms Keegan said: "I wasn't really talking about anyone in particular. It was an off-the-cuff remark after the news interview had finished, or apparently after it had finished.
"I would like to apologise for my choice language, that was unnecessary."
She indicated she was frustrated with those who have not responded to questionnaires asking about whether schools have the dangerous aerated concrete present.
She said: "It is frustrating because we're doing everything now to take a leading position to be on the front foot, to put all the support in place that responsible bodies and schools need.
"It's also frustrating that we've got some questionnaires that still are not there, we've been chasing and chasing them, we've written again today to say you need to get your questionnaires in by the end of the week."
Pressed on whether she was frustrated with councils, her predecessor as education secretary or Prime Minister Rishi Sunak, Ms Keegan said: "No it's not, it's nobody in particular."
But taking aim at ITV's Mr Hewitt, she said: "Actually it was the interviewer, because the interviewer was making out it was all my fault, and that's what I was saying, do you ever go into these interviews where anyone ever says anything but 'you've just done a terrible job'."
Sir Keir Starmer said the episode showed ministers appeared to be attempting to "pass the buck" for school building closures caused by the concrete issue.
The Labour Party leader, asked by broadcasters in Westminster about Ms Keegan's remarks, said: "I think this whole situation is descending into farce.
"The Government has dropped the ball here, failed to prepare.
"The Prime Minister bears responsibility for some of the key decisions along the way.
"And instead of coming out today and saying, 'This is what we're going to do to fix the problem, which we have made a lot worse', you've got members of the Cabinet coming out trying to blame other people, trying to blame people within their own teams and to say, essentially, 'Put responsibility anywhere but on the Government'.
"That is not what Britain deserves.
"And obviously what is now being said shows the extent to which there is this passing the buck within the Cabinet. Is Rishi Sunak strong enough to do anything about it? I doubt it."
Asked whether Ms Keegan should remain in post following her unguarded comments, Sir Keir said that was the Prime Minister's decision to make.
A No 10 source told Sky News Rishi Sunak had “full confidence” in Ms Keegan, adding the comments she made about not being thanked for her work over the crisis were “wrong”.
Hundreds more schools in England could be affected by crumbling concrete, Mr Sunak acknowledged on Monday morning as he faced accusations he failed to fund a programme to replace ageing classrooms.
The Prime Minister insisted that 95% of England's schools were unaffected, leaving open the possibility that more than a thousand could still be impacted by concerns over reinforced autoclaved aerated concrete (Raac).
Downing Street said the total number was expected to be in the hundreds rather than the thousands and the vast majority of schools would not be affected.
More than a hundred schools in England were told they could not fully open just days before the start of the autumn term because of safety fears over the use of Raac.
Pupils face being taught in temporary classrooms, on different sites or even forced into pandemic-style remote lessons.
Mr Sunak said: "New information came to light relatively recently and it's important that once it had, that the Government acted on it as swiftly as possible.
"Of course I know the timing is frustrating, but I want to give people a sense of the scale of what we are grappling with here: there are around 22,000 schools in England and the important thing to know is that we expect that 95% of those schools won't be impacted by this."
If, as Mr Sunak said, 5% of schools are impacted, that would mean 1,100 are affected.
The Prime Minister's official spokesman said : "I think the Prime Minister was providing reassurance to parents, pupils and schools that the vast majority - we believe more than 95% won't be affected."
A former top official at the Department for Education suggested Mr Sunak had declined a request for funding to rebuild more schools while he was chancellor.
Jonathan Slater, who was permanent secretary at the Department for Education (DfE) from May 2016 to August 2020, said the Treasury knew there was a "critical risk to life" if the schools programme was not funded.
Mr Slater said up to 400 schools a year need to be replaced, but the DfE got funding for 100 while he was the senior official, which was "frustrating".
But when he left the department he said he was "optimistic" that a push for extra funding to build 200 a year would be successful.
He told BBC Radio 4's Today programme: "The actual ask in the Spending Review of 2021 was to double the 100 to 200 - that's what we thought was going to be practical at first instance.
"I thought we'd get it, but the actual decision that the chancellor took in 2021 was to halve the size of the programme."
But Mr Sunak insisted that 50 schools a year was in line with what had taken place over the previous decade.
He told reporters that Mr Slater's attack on his record was "completely and utterly wrong".
"Actually, one of the first things I did as chancellor, in my first spending review in 2020, was to announce a new 10-year school re-building programme for 500 schools.
"Now that equates to about 50 schools a year, that will be refurbished or rebuilt.
"If you look at what we have been doing over the previous decade, that's completely in line with what we have always done."
Shadow education secretary Bridget Phillipson said: "The defining image of 13 years of the Conservative-run education system will be children sat under steel girders to stop the roof falling in."
She said Mr Sunak "bears huge culpability for his role in this debacle", adding: "Ministers need to come clean about the number of schools affected, what they knew, and when they knew, about the risks posed by Raac so that parents can be reassured their children are safe at school."
Liberal Democrat education spokeswoman Munira Wilson said: "This bombshell revelation shows the blame for this concrete crisis lies firmly at Rishi Sunak's door.
"He slashed funding to repair crumbling classrooms when officials said it needed to be increased. Now children and parents across the country are paying the price for this disastrously short-sighted decision."
Schools in Scotland, Wales and Northern Ireland are also being assessed for Raac.
The Scottish Government has said it is present in 35 schools, but that none poses an "immediate risk" to pupil safety.
The Welsh Government said two schools on Anglesey which had been due to open for the autumn term on Tuesday would be closed temporarily.