South Korean police said Wednesday they are pursuing criminal charges against 715 individuals related to a nationwide illegal gambling operation, which is thought to have brought in around 100 billion won ($72 million) in revenue.

Busan Metropolitan Police Agency arrested seven individuals suspected of running a poker-themed bar franchise with 15 local branches across the country that conducted an illegal gambling operation from March 2021 to April this year. The others are being investigated without physical detention, including 590 alleged clientele.

The law bans Koreans from gambling -- both in and outside the country -- as well as any gambling within Korean borders, aside from at a few designated establishments granted an exception by authorities. The establishments in question were "hold 'em pubs," which normally provide poker games for fun, but some of which are used as a cover for operating de facto casino businesses.

A suspect in his 50s is believed to have conducted regular meetings with store owners of his illegal franchise, discussing operational methods while requiring them to sign nondisclosure agreements.

The gambling venues held low-risk tournament-type poker events frequently to maximize profit. Participants were rewarded points for their winnings, which were unofficially exchanged for cash at stairways and smoking rooms to avoid detection.

The illegal pubs are believed to have generated 100 billion won in revenue, with 47.9 billion won in profit for the operators.

Operators of the illegal gambling ring even purportedly planned to open an overseas franchise, which was thwarted by the recent bust.