Police have shut down a narcotics manufacturing and packaging centre in Mong Kok, following the arrest of a man and three women and the seizure of $1.6 million in drugs including cocaine and heroin.

After intensive investigation, officers identified the key members of the syndicate and mounted a surveillance operation.

A 42-year-old man was intercepted on Soy Street at about 7.20am yesterday and a packet of heroin weighing about 16 grams was found in his possession.

Officers searched his home and another flat on Pak Po Street, which led to the further find of 1.8kgs of heroin, 634 grams of cocaine, 139 grams of ice, 476 grams of cannabis and 2kgs of caffeine.

Some drugs packing and manufacturing paraphernalia including a hydraulic jack, a mould and a scale, $400,000 cash and other foreign currencies were also seized.

In a related development, officers stopped three women aged 22 to 24 at the junction of Portland Street and Hamilton Street, and found a block of heroin weighing 375 grams. It is believed they are couriers for the syndicate.

The four, arrested for manufacturing and trafficking in dangerous drugs, remain in custody for inquiries.