Macau police arrested 11 people, including a 47-year-old businessman surnamed Chau, on Saturday for offenses of illicit operation of gambling and money laundering.

While officers did not directly name Alvin Chau in Sunday’s press conference about the arrest, the Suncity Group chairman matches the mastermind's surname and age.

Police said the arrested admitted to establishing the overseas gambling platform, but refused to cooperate in revealing more details.

Local media reported that the arrested have been transferred to the Public Prosecutions Office on Sunday afternoon. Chau was transferred to the prison for his custody at around 6am Monday, following recommendation by the prosecution.

Days following his arrest, mainland authorities highlighted the alarming rise of illegal casinos and the trend of establishing gambing platforms overseas.

Speaking at a press conference on Monday, the Supreme People's Procuratorate -- China's highest prosecution office -- said mainland authorities have prosecuted 63,238 individuals in over 25,000 cases of illegal casinos on the mainland from January to September this year.

It stated that the number of defendants charged and cases involved increased by 45 and 49 percent respectively, as compared to their average numbers between 2018 and 2020.

The Procuratorate said criminals have made use of online card games or mobile applications to sugarcoat such illegal gambling operations, disguising it as a form of entertainment to entrap people into gambling.

It said overseas elements were involved in most of these cases, with the criminals recruiting locals as proxies to enable mainlanders to place bets online.

Among the 13,329 people prosecuted for cross-border crimes from January to September this year, 1,379 of them were involved in running illegal cross-border gambling operations, including in overseas countries, Hong Kong and Macau.

Such crimes accelerated capital outflow, and illegal gambling often involves money laundering, fraud, blackmailing, and false imprisonment, according to the office.

As many of such crimes were often committed outside of mainland China, it is difficult to bring the culprits to justice, the Procuratorate said.

Wenzhou authorities said last Friday their investigation had found that Chau formed a junket agent network in the mainland to help citizens engage in offshore and cross-border gambling activities.

Chau also set up an asset management company in the mainland to help gamblers make cross-border fund transfers, the Wenzhou City Public Security Bureau said on its Weibo account.

As of July 2020, the "crime syndicate" led by Chau had 199 shareholder-level agents, more than 12,000 gambling agents and over 80,000 punter members.