Hong Kong police have made their largest seizure of dangerous drugs this year, swooping on a factory building in Fanling, where a haul worth more than HK$170 million (US$22 million) was hidden inside soft-drink bottles.

Two men, aged 27 and 33, who police said were members of a transnational drug syndicate have been arrested and charged with drug trafficking.

Officers from the Narcotics Bureau raided a flat in a factory building in the industrial area at On Lok Tsuen in Fanling on Thursday, when they found a total of 178kg of heroin, Ice – or crystal methamphetamine – and ketamine concealed in 305 soft-drink bottles.

The bottles were hidden among 1,000 boxes containing more than 10,000 bottles, with 88kg of Ice found in 150 bottles, 82kg of heroin in 143, and 8kg of ketamine in 12.

The two arrested men, both from countries in South Asia, were intercepted as they moved goods from the flat, according to police. An initial investigation showed they had no triad backgrounds.

Speaking at a Sunday press conference, Superintendent Raymond Chou said there had been a surge in drug seizures this year, describing the situation as “worrying”.

There have been four cases detected by police and customs this year involving seizures worth more than HK$100 million each, including the case on Thursday.

Chou said there had been significant increases in seizures of certain categories of drugs. About 348kg of Ice and 43kg of heroin were confiscated in the first six months of this year, respectively, compared with 16kg and 23kg a year ago.

The seizures of the two drugs this year had, in fact, surpassed the total of last year and 2018 combined.

“Due to wars and social unrest, economic downturn and changes in the anti-drug policies of some countries … there has been a continuous upwards trend in global drug production and seizure,” Chou said.

And due to tightened immigration control measures amid the Covid-19 pandemic, the mode of drug trafficking had shifted to cargo import, he added.

“On one hand, global drug production has remained at a high level, [and transporting via air] generally involves a relatively high cost … [so] it may cause drug dealers to smuggle more drugs at one time, leading to an increase in the number of large seizures,” Chou added.

Chou also noted the attempt to hide the most recent haul inside drink bottles was not a particularly sophisticated tactic, saying the force had discovered narcotics in everything from wine bottles to large machines to durian.

Investigators have yet to trace the source or ultimate destination of the latest haul.

The bureau’s Chief Inspector Ip Sau-lan said: “The amount of drugs and the goods that were hidden was quite large. We need to determine their origin. Whether it was to supply the local market or be transited will be a focus of our investigation.”

She said she believed no drugs from the syndicate had yet been circulated in the market.

The arrested men, claimed to be a porter and jobless, respectively. While one possessed a Hong Kong identification card, the other was a holder of a form that did not allow for employment in the city.

They were charged with one count of drug trafficking and will appear in Fanling Court on Monday.