City of London police have arrested three people for running an unofficial version of Disney's game Club Penguin.
Police, acting on the wishes of Disney, took down the website, which claimed to have millions of registered users.
It comes after a BBC investigation in 2020 witnessed players simulating sex and exchanging racist and anti-Semitic abuse on another unauthorised clone of the children's game.
Police have released the suspects as they investigate copyright offences.
Disney's Club Penguin launched in 2005 and was one of the first social networks for children.
It had more than 200 million players at its peak, who explored a cartoon world - walking, talking and playing mini games using penguin avatars.
While anybody could join the original website, content filters and human moderators were employed to stop inappropriate messages or personal information being shared.
But Disney closed the website in 2017.
Since then, unofficial clones of the website have been set up. These so-called 'private servers' were launched using stolen or copied source code, and can easily be found by children searching the internet.
Club Penguin Online was the largest of the unauthorised clones and the subject of a BBC investigation in May 2020.
Its popularity exploded during the coronavirus pandemic, with seven million registered players.
The BBC investigation found racist, homophobic, anti-Semitic and sexual messages flowing freely on the unauthorised platform, which saw children playing alongside adults.
Disney said it was "appalled" by the website and ordered it to close or face legal action.
But many players simply moved to another major site, Club Penguin Rewritten, which - nearly two years on - has now been closed.
The site included in-game advertising, although it is not known how much money was generated.
One player, who spent time on both sites, told the BBC: "The game had been booming ever since Club Penguin Online's [CPO] shutdown, as that is where the CPO player population migrated to. However, that may have worked against them in the end."
Another user contacted the BBC claiming the site was 'unsafe' because of poor moderation.
Detective Constable Daryl Fryatt, from the Police Intellectual Property Crime Unit (PIPCU) at City of London police, confirmed the seizure of the site and arrests.
"Following a complaint under copyright law, PIPCU have seized a gaming website as part of an ongoing investigation into the site.
"Three people were arrested on April 12 on suspicion of distributing materials infringing copyright, and searches were carried out," he said.