Australian betting operator Tatts Group is not buying its international rival’s claim of why the Australia has to legalize online in-play betting.

Failing to regulate the growing sports betting market would push the Aussie punters onto the international black market and would cause the Australian government to lose up to AUD2.2 billion ($1.6 billion) in tax revenue by 2020.

That’s the warning from international gambling operators, which led the Australian government to review its existing online betting laws.

The Barry O’Farrell-led review focuses on how to combat the negative effects of international online gambling sites offering services to Australian gamblers and their ability to offer in-play sports wagers, which the 2001 Interactive Gambling Act (IGA) restricts to telephone or retail wagering outlets.