Two of the owners of Le Monde have hit out at the newspaper over its part in revealing how HSBC’s Swiss banking arm helped wealthy customers dodge taxes – with one declaring: “It wasn’t for this that I allowed them to gain their independence.”

Journalists and editors at the French daily – which collaborated with the Guardian and other news organisations on the investigation – reacted with fury to the criticism from the two businessmen and vowed to “scrupulously enforce” the paper’s editorial independence.

Le Monde owner's criticism of HSBC leak coverage lays bare fragility of press freedom Read more

The story has triggered a debate about press freedom in France after Pierre Bergé, president of Le Monde’s supervisory board, attacked the paper on RTL radio, accusing it of “informing” on the business people, politicians, criminals and celebrities named in the HSBC files.

“Is it the role of a newspaper to throw the names of people out there? ... I don’t want to compare it to times past but all the same, informing is informing,” said Bergé, partner of the late fashion designer Yves Saint Laurent and co-founder of the couture house. He accused Le Monde of “populism” and “flattering the worst instincts”.

“It wasn’t for this that I allowed them gain their independence,” declared the 84-year-old, one of a trio of tycoons that pulled the paper back from the brink of bankruptcy in 2010. He added that he “condemned” the paper’s methods.

Matthieu Pigasse, head of the Lazard investment bank in Paris and another member of the trio owning Le Monde, also voiced his concerns over the reporting. “It’s true that there is a balance to be struck between disclosing information that is in the public interest and falling into a form of fiscal McCarthyism and informing,” he said, while stressing he was “proud” of Le Monde’s work. Pigasse also has interests in several French media.

The union of Le Monde journalists hit back at Bergé. “We forcefully condemn, as on previous such occasions, this intrusion into editorial content. The role of shareholders is to define company strategy and not to try to lean on news sense,” it said. The union said its journalists continued to work calmly and responsibly.

Le Monde’s editorial management also criticised the “attacks by Pierre Bergé against Le Monde journalists”. “We assume the editorial choices made during this investigation and during the publication,” the editors said, vowing to “scrupulously enforce” the paper’s editorial independence.

Last year, Bergé angered Le Monde’s union when he publicly criticised the paper’s books coverage and attacked its literary critic on Twitter.

In 2013, Bergé, who backed the government’s same-sex marriage bill, tweeted a series of furious comments when the paper carried a full-page advert for an anti-gay marriage campaign, suggesting the people who booked the ad were not worthy of working at the paper.

Le Monde’s third co-owner, telecoms magnate Xavier Niel, made no comment about the HSBC story. The trio signed an agreement with the paper in 2010 guaranteeing its editorial independence.