A Sky News investigation has revealed that illegal online casinos are allowing children to sign up and gamble using their Roblox accounts. Roblox is a popular gaming platform, and around 42 percent of its users are 12 and younger.

The casinos accept Roblox’s in-game currency, Robux, for the purchase of virtual gambling chips. These chips can then be used to play casino games. Winnings can be withdrawn as cryptocurrency and converted into real cash.

A U.S. teenage user said he did not realize he was committing a criminal offense, telling Sky News, “I didn’t even know what gambling was. I just thought it was something you could do to make extra money.” He said that his mother tried to get him to stop but he “liked the adrenaline of doing bigger and bigger bets.”

The UK Gambling Commission (UKGC) has since blocked three Robux casinos in the country, namely RBLXWild, Bloxmoon and BloxFlip.

“At the end of the day, illegal casino operators are criminals,” UKGC CEO Andrew Rhodes told Sky News. “Criminals will always try and find new ways to exploit people, including children.”

A Roblox spokesperson says the company does not endorse the casinos and will “welcome further law enforcement action and vigilance from web hosting providers to shut down sites like this.” However, parents of five U.S. children who used these casinos have sued the company.

“They knew for years it was happening, and they didn’t do anything,” James Bilsborrow, the leading lawyer in the case, told Sky News.