Customs officers on Friday said they had made their largest seizure of illicit cigarettes in 21 years, as part of a crackdown.

Some 78 million cigarettes with an estimated market value of about HK$220 million were confiscated.

It was one of 20 cigarette smuggling cases uncovered as part of a week-long operation from July 6-12.

Officers said they found 97 million suspected illicit cigarettes in total, in warehouses, shipping containers and a truck they pulled over in Yuen Long.

Twenty-three people, aged between 23 and 71, were arrested.

Customs said they have seized 259 million illicit cigarettes since January this year, which is a 21 percent increase on the same period last year.

Lee Hoi-man, deputy head of the Revenue Crimes Investigation Bureau, said supply chain disruptions last year due to the pandemic might have hindered cigarette smuggling.

"Last year, it was difficult to find a container and even difficult to ship a container from one place to another. During the second quarter of this year, the condition seemed to be stable. They took the opportunity to smuggle a large amount of cigarettes to Hong Kong and then store them in Hong Kong, waiting for the buyers," he said.

Lee said he believes that smugglers had planned to export around 40 percent of the seized cigarettes to other places.