Hong Kong customs has arrested four people and seized HK$140 million (US$18 million) worth of slimming and cosmetic injections, along with erectile dysfunction pills, in a crackdown on smuggled illicit medicines.

The suspects, aged between 26 and 61, comprise two mainland Chinese men and two local women, the Customs and Excise Department said on Monday. Investigations are ongoing, and the department has not ruled out further arrests.

The department said that since stepping up enforcement in January, it had uncovered 100,000 injections, 340,000 tablets and 60kg (132lbs) of controlled medicines across nine smuggling cases.

Seven cases involved slimming injections, while the others related to cosmetic anti-wrinkle injections and erectile dysfunction pills.

Anthony Tang Cheuk-wai, divisional commander of the department’s special investigation division, said injectable products were in high demand in the city, noting that overseas purchases could cost up to eight times less than obtaining a medical prescription.

But he cautioned that most of the seized injections and medicines were not properly stored at low temperatures, raising concerns about their quality and safety.

“Some of these medicines must be stored at 2 to 8 degrees Celsius (35 to 46 Fahrenheit),” Tang said. “But to cut costs and increase mobility, the suspects did not use refrigerated equipment during transport and failed to meet storage requirements.”