Three men aged 27 to 45 have been jailed for up to 21 years for dangerous drugs manufacturing and trafficking.

A 41-year-old man was sentenced to 21 years while his 45-year-old accomplice received 20 years. A 27-year-old defendant was sentenced to 10 years' imprisonment.

Police were watching a residential building on Shanghai Street in Yau Ma Tei on January 8.

The younger man was acting suspiciously when he left a flat inside the building. Officers stopped him after a brief struggle.

Police then entered the flat where the other two men were found. The 41-year-old was found trying to flush some dangerous drugs down the toilet.

Officers seized about 380 grams of a mixture containing about 243 grams of heroin. The haul could have fetched over $126,000 if sold in the retail market.

They also seized some manufacturing and packing equipment, such as a hydraulic jack, cylindrical moulds, blender and electronic scale.

The trio was arrested and charged for making and trafficking in dangerous drugs.