Police have arrested 12 people and seized a quantity of air guns suspected of being illegally modified on Wednesday as part of a crackdown on illegal firearms and ammunition in Hong Kong.

Officers seized 40 air guns from a shop at 224 Wan Chai Road and then raided a warehouse in Chai Wai, where they found and seized almost 4,000 more air guns.

The power of approximately 400 of the guns seized were suspected of having modified to exceed the Hong Kong legal limit of 2 Joule, a spokesman said.

The family-run shop, which has been in operation for 15 years, imported air guns and parts from overseas and allegedly modified them for customers, the spokesman said.