HONG KONG- Police said on Friday they had busted an illegal gambling outfit that racked up HK$5 billion (US$645 million) in wagers on the World Cup in a week — including a single bet of US$5.1 million.

Twenty-two people were arrested in the operation, which police described as the largest-ever case of its kind in the Asian gambling enclave, according to reports.

“Records showed that (betting) had reached HK$5 billion. It has already surpassed the biggest betting case in history,” Suen Kam-fai, a spokesman for the Macau police told Hong Kong’s Cable News channel.

More than HK$2 million (US$258,029) in cash was found in Macau hotel rooms that served as the ring’s operating base, along with computers, records and other items.

Police found evidence of the US$5.1 million bet during the bust, according to the South China Morning Post.

Footage shown on the channel showed those arrested wearing black masks and handcuffs, lined up during a press conference.

The group was composed of four Hong Kong residents, nine Malaysians and nine from the Chinese mainland, the Post reported.

Singapore authorities last year placed leaders of a global match-fixing ring operating from the city-state in indefinite detention after uncovering plans to rig the World Cup, according to a book released Monday.

Doha-based watchdog International Centre for Sport Security warned in a May report that Asian-dominated criminal groups are laundering more than US$140 billion in illegal sports betting annually.