The 48-year-old founder of Suncity Group pioneered the junket industry that brought high rollers from mainland China to Macau, the only place in the country where casinos operate legally.

At its peak during the 2010s, junkets contributed the bulk of gaming revenue for the former Portuguese colony, which boasted a pre-pandemic casino industry bigger than Las Vegas.

Chau's downfall coincided with Chinese President Xi Jinping's years-long anti-corruption drive, which has included much closer scrutiny of corrupt officials who might travel to Macau to place bets and launder money.

Prosecutors charged Chau with 289 counts of fraud, money laundering and illegal gambling.

Judge Lou Ieng Ha on Wednesday found Chau guilty of fraud, running a criminal syndicate and operating illegal bets, but acquitted him on the money laundering charge.

Suncity under Chau's leadership "conducted illegal gambling for unlawful gains for a long time", she said in her ruling, and sentenced him to 18 years behind bars.

The trial began in September and centered on alleged under-the-table bets worth HK$824 billion ($106 billion) over eight years, which defrauded Macau of tax revenue exceeding HK$1 billion.

Chau, who was charged alongside 20 co-defendants, was also accused of facilitating proxy betting for Chinese customers to gamble remotely in casinos based in Southeast Asia.

The defence acknowledged that under-the-table betting existed in Macau, but pointed to the lack of direct evidence implicating Chau, Suncity executives or employees.

Addressing the court in December, Chau said his company had never run into legal trouble in more than a decade of operating VIP rooms in casinos worldwide.

"I don't know why [Suncity] is deemed a criminal syndicate," Chau said, according to local media.

"My colleagues have not seen a cent of criminal proceeds up until now... We have never paid additional compensation for illegal acts."

Chau's legal woes began in November 2021 when authorities in the mainland city of Wenzhou issued a warrant for his arrest for running an illegal gambling syndicate.

Macau authorities then arrested him and other senior company executives two days later but chose to charge them locally, citing a concurrent investigation based in the city.

Macau has a separate legal system from the Chinese mainland, largely based on Portuguese law.

In September, a court in Wenzhou convicted 36 people related to Chau and Suncity based on allegations that partly overlapped with the Macau case.

After the arrests, Suncity shut down all its VIP rooms and a number of casino operators followed suit, some also citing Covid-related business pressures.

It signaled a shift in Macau's gaming industry as the government strengthened its regulatory muscle with Beijing's backing, which took the form of a legal amendment last June.

Another high-profile junket boss Levo Chan, Chau's onetime rival, is also being prosecuted separately for fraud, money laundering and running a criminal syndicate.

"The junket model was one of the prime movers for money laundering for as long as it was prominent," gaming consultant David Green told AFP.

"The casinos themselves can't afford to take the risk of being held jointly liable with the junkets for their misdemeanors."

Casino operators Wynn Macau, SJM Holdings, MGM China, Sands China and Galaxy Entertainment Group have asked the court to award damages for revenue losses attributed to Suncity.