Boris Johnson told children on a school visit that journalists are “always abusing people”.
The prime minister claimed he became a politician because he felt “guilty” about “attacking” people in his former career as a journalist.
Johnson told the pupils: “When you’re a journalist it’s a great, great job – a great profession.
“But the trouble is that sometimes you find yourself always abusing people, attacking them.
“Not that you want to abuse or attack them, but being critical.
“Maybe you feel sometimes a bit guilty about that because you haven’t put yourself in the position of the person you’re criticising.
“So I thought I’d give it a go.”
Labour said Johnson’s “troubling” comments “probably say more about his own career”, while the National Union of Journalists (NUJ) said the "banal disparaging of journalists as unfeeling bullies" revealed he has "complete disdain for journalism and press freedom".
The Society of Editors said Johnson's comments were "ill chosen" and stressed "no serious, professional journalist would agree that they set out to abuse people".
Johnson has been accused of racism and homophobia following articles he wrote which compared burqa-wearing Muslim women to “letterboxes”, called gay men “bumboys” and described Black Africans as “piccaninnies” with “watermelon smiles”.
The PM was also sacked by the Times in 1988 for making up a quote in a front-page story, and also took part in an infamous phone call with his former Eton friend Darius Guppy, recorded in 1990, where Guppy asks Johnson to find the address of a News of the World journalist who has upset him. Despite Guppy’s apparent plans, the journalist was never attacked.
Despite repeated claims that the government defends press freedom, it has been criticised in recent weeks after equalities minister Kemi Badenoch attacked a HuffPost UK journalist on Twitter for privately asking her a question.
Johnson’s press secretary Allegra Stratton defended the PM.
Asked if, given his remarks, the PM regrets comments about “picanninies” and “bumboys”, Stratton told reporters: “Your job is to constantly challenge. And that’s something that makes all of us in government better.
“I think that’s all he was doing is describing the role of journalism is to constantly, constantly be asking the details and the finer points.”
Labour’s shadow media minister Chris Matheson said: “For Boris Johnson to say journalists are ‘always abusing people’ probably says more about his own career.
“It is particularly troubling coming so soon after the prime minister stood by one of his ministers who attacked a journalist who was just trying to do her job.
“We know from Donald Trump that these kind of assaults on the free press are dangerous and designed to stir up distrust and division.
“Boris Johnson should withdraw these remarks and apologise.”
NUJ general secretary Michelle Stanistreet said: "Great to know we can trust in the prime minister to inspire the next generation of journalists.
"He may have penned columns for a living but this banal disparaging of journalists as unfeeling bullies reveals a prime minister with complete disdain for journalism and press freedom.
"It also demonstrates the PM’s lack of respect for the vital role journalists have played in keeping the public informed during a global pandemic, and his own crass lack of empathy for the worsening harassment, abuse and intimidation being meted out to journalists right now, simply for doing their job.”
Ian Murray, executive director of the Society of Editors said: "The prime minister's choice of words to describe his former profession are obviously unfortunate and ill chosen.
"If he was attempting to explain to students that journalists are required to challenge people, especially those in positions of power and authority, and this may make you unpopular at times, then he is correct.
"However no serious, professional journalist would agree that they set out to abuse people and such language undermines respect in our profession."