Hong Kong police have arrested 127 people in a six-month undercover operation against a Vietnamese-led crime syndicate accused of running loan-sharking rackets charging interest rates of up to 3,700 per cent, as well as illegal gambling and unlicensed bars in West Kowloon.

The syndicate is also alleged to have helped illegal immigrants find shelter and work, with police raiding eight premises on October 8 and 9.

Among those arrested were 10 alleged core members, including the suspected leader, a Vietnamese woman holding a Hong Kong identity card.