Police have arrested 20 people after a gang allegedly gave foreign domestic helpers cash to open bank accounts used to process HK$10 million in criminal proceeds.

Among the suspects picked up on suspicion of conspiracy to launder money were 14 Indonesian migrant workers.

A helper is suspected of having acted as an intermediary for a syndicate to recruit others, with meetings arranged at locations such as parks, fast food restaurants and hotel rooms.

Officers on Monday said they believe the helpers were paid between HK$1,000 and HK$2,500 for opening accounts, which were then managed by the syndicate.

"For foreign domestic workers, the amount [allegedly] paid is relatively high compared to their salaries. That also was the main incentive for them to [allegedly] sell their bank accounts," said Chief Inspector So Chi-bing.

The bank accounts are suspected of being linked to 39 cases of fraud involving losses of HK$5.4 million, police added.