Police in Hong Kong and mainland China arrested 42 people including illegal Vietnamese immigrants and the gangsters who smuggled them in during raids last Wednesday.
The mainland police caught 31 in hideouts in Guangzhou and Shenzhen while Hong Kong officers arrested 11 others.
The exact number of Vietnamese nationals arrested is unclear yet. But police said there were at least five Vietnamese among the core members of the gang, the South China Morning Post reported.
Preliminary investigation found the gang had been in operation for a year and smuggled more than 100 Vietnamese into Hong Kong.
The illegals would be taken to Guangxi Province from Vietnam by land for HK$30,000 (US$3,900) each. They would hide in Guangzhou and Shenzhen before going to Hong Kong by speedboat.
The police said the racket has been under investigation since March.
The report cited a police source as saying that the illegal immigrants were given fake identity cards to find jobs, mostly at construction sites.
The investigation is continuing, and there can be more arrests, the police said.
The number of Vietnamese illegal immigrants arrested in Hong Kong has dropped from 189 a month last year to 112 now, the report said, citing official data.