China’s mobile message service WeChat is cracking down on unauthorized ‘red envelope’ gambling rings on its network.

WeChat announced this week that it was forced to take action after many of its 700m active users refused to stop using the service’s ‘Hongbao’ function to organize informal gambling rings.

Hongbao, which made its debut in 2014, allows WeChat users to exchange virtual credits that can be used for online purchases or withdrawn as cash. The name comes from the Chinese practice of exchanging red envelopes containing money on special occasions. During this February’s Lunar New Year’s Eve, WeChat processed over 8b Hongbao envelopes, eight times higher than the previous year.

WeChat also offers a function that allows users to send Hongbao to a group of recipients with options to distribute the money evenly or on a purely random basis, with some members of the group winning big and others receiving a pittance.