Local police officials in China seized more than $1.5 million worth of cryptocurrencies as part of a crackdown on gambling during the 2018 FIFA World Cup.

Chinese state-run media outlet Xinhua reported on July 11 that authorities first noticed the unnamed gambling platform in May following advertisements that claimed it would “accept international recognized cryptocurrencies including bitcoin, ether and litecoin” in order to draw in users. An investigation was launched soon after, according to the outlet.

The special investigation team discovered that the site, based overseas, utilized a traditional online gambling model coupled with cryptocurrency payments. Xinhua cited “regulatory loopholes” by which the site was able to secure profits by hiding proceeds using those currencies.

All told, over the course of eight months, some 333,000 users used the site, which reportedly saw an estimated transaction volume of at least $1.5 billion.

Now, authorities have arrested six organizers of the site and confiscated $1.5 million worth of cryptocurrencies as well as $750,000 in renminbi deposits from their bank accounts.

A spokesperson from the police department in Guangdong province said that the task force will continue working to”maintain a highly concentrated attention” on cracking down online soccer gambling and advised soccer fans to watch the games “rationally and consciously.”

World Cup Image via Shutterstock