Customs officials on Saturday said they have uncovered the first ever underground cigarette factory in Lau Fau Shan. They said the facility was equipped with a complete production line.

The authorities also uncovered a cigarette storage warehouse in Man Kam To and seized over 20 million suspected illicit cigarettes and about 3.5 tonnes of processed tobacco.

They said the haul had a market value of HK$120 million.

Four men, aged 29 to 46 were arrested.

Customs division commander Lam Chak-lun said the investment in this cigarette production line had been huge.

“First, it was located in a large-scale, airtight prefabricated building. And the building was heavily insulated with industrial soundproofing material, hidden inside a factory,” he said.

“It can effectively block light and noise generated while the machines are running. It was also powered by solar panels, likely to avoid drawing attention from authorities due to high electricity usage.”

The authorities said they believed the production line was on a test run and had only been operational for a short time.