A clique of French journalists has been accused of bullying female colleagues via social media.

Six people have been suspended for their role in the closed Facebook group Ligue du LOL, a macho online “boys’ club” that reportedly harassed female and minority ethnic journalists for years.

The group, believed to have had about 30 members, is said to have spread pornographic memes online and doctored photos to humiliate its victims.

What group members claim started as dubious humour in private exchanges, however, appears to have soon degenerated and spread on to the wider web mostly through Twitter.

It seems some of the victims were aware of the identity of a number of their alleged harassers – those members of the Ligue who posted on social networks under their real names – but were afraid to speak out.

The league’s founder, Vincent Glad, was suspended by Libération newspaper on Monday after the paper verified the existence of the group during a fact-checking exercise.

Among others being disciplined are one of Libération’s senior online editors, Alexandre Hervaud, and David Doucet, the web editor-in-chief of Les Inrockuptibles, a high-profile music and culture magazine.

Doucet wrote on Twitter: “I was a member of the Ligue du LOL for two years. I left the group six years ago … in the small world that was then Twitter, I saw that certain people were regularly targeted but I never guessed the depth of the trauma suffered. I was cowardly and too happy to be one of this band that the Twittersphere then admired, to intervene … I would like to say that I never did any of the photomontages, took part in raids or participated in the evenings described. This speaking out has above all made me realise that I was one of the tormentors.”

Hervaud wrote a long message on Twitter apologising for “condescending” tweets he had posted on Friday when the scandal first broke, and said he offered “sincere if belated apologies to those he had hurt”. He said the Ligue “never aimed to coordinate hateful campaigns targeting anyone. But it doesn’t serve to minimise or deny the evidence. The permanent spirit of mockery and cynicism of the group obviously influenced the actions of certain more borderline members, notably those covered by anonymity, who, by the snowball effect inspired other internet users outside the group.” He admitted some of the victim statements had “literally twisted my stomach”.

Christophe Carron, the editor of the French edition of the online magazine Slate, also admitted having been a member of the group but denied “socially or professionally damaging anyone … or harassing anyone”.

The Libération director, Laurent Joffrin, announced an internal investigation. “We have nothing to hide,” he said.

In an apology published on Twitter, Glad said he had “created a monster that escaped”.

“The object of the group was not to harass women, just to amuse ourselves. But quickly, our way of amusing ourselves became very problematic and we didn’t realise this. We thought that everyone visible on the internet, by a blog, or Twitter account or something else, deserved to be mocked,” Glad wrote. He added that he didn’t realise that this could “become a hell for the people targeted”.

Other Ligue members who have been suspended from their roles include Guilhem Malissen, a humorist on food podcast Bouffons, who apologised on Twitter; Renaud Loubert-Aledo, who worked at Publicis Consultants; and Guillaume Ledit, a journalist with Usbek & Rica, a quarterly magazine “exploring the future”. Another member, Stephen des Aulnois, the founder of online pornographic magazine Tag Parfait, said he was suspending the website and stepping down voluntarily.

The videomaker Florence Porcel said she had been the victim of an “online lynching” and had been humiliated when a member of the Ligue du LOL called her pretending to offer her a job, while recording the conversation.

“When the recording was made public, I cried from shame, humiliation and fear for three days. I didn’t want to go out,” she said. Porcel said she had also featured in a “very degrading pornographic photomontage … that was their method”. Doucet admitted in a tweet that he had posed as a recruiter from a television station and called Porcel. “I am sorry,” he wrote.

The blogger and author Matthias Jambon-Puillet recounted, under his pseudonym Benjamin LeReilly, receiving anonymous insults and that a photomontage of him performing a sex act was sent – purportedly from him – to minors. Although he does not know who sent the insults, he said he believed they came from members of the league.

The journalist Mélanie Wanga said she believed the league’s members were finally getting what they deserved. “Imagine being a young, black woman journalist talking about blackface and apartheid and getting this stuff multiplied by 20 from your ‘colleagues’,” she said, sharing tweets she suspected had come from unidentified members of the league.

Capucine Piot, a former journalist now in marketing, said she had been the victim of several “mocking” photomontages and videos criticising her appearance. “It was very hard for a developing young woman. After reading so much dirt about myself … I was convinced I was worthless,” she tweeted.

Other victims have remained anonymous. “Those guys, they thought they were making jokes but they were ruining our lives,” said one. France’s minister for digital affairs, Mounir Mahjoubi, described the men behind the Facebook group as “losers”.

“It is a group of guys high on their power at being able to make fun of other people. Except that their mockery had an effect in real life,” he said.