Drug trafficking using international shipping has sharply increased as overseas travel became nearly impossible and online purchases went up amid the coronavirus pandemic, a local customs office said Tuesday.

The Incheon Main Customs said it busted 189 cases of drug smuggling into South Korea in the first quarter of this year and has referred 16 suspects to the prosecution.

Of the total, 182 cases involved international shipments, compared with the 118 cases reported during the same period last year.

The volume of drugs hidden in parcels or letters reached 96 kilograms, up 68 percent from 57 kg a year ago.    

In particular, the amount of confiscated methamphetamine more than doubled to 58 kg from 23 kg over the same period. The total amount of illicit drugs seized by the office reached 99 kg.

Drug trafficking methods have become very sophisticated to avoid surveillance and detection, the customs office said.

Many drug dealers buy drugs through secure messenger services or the dark web, an area of the internet only accessible through specific software or authorization, and make the payments via cryptocurrency brokers.

The drugs are then shipped into the country, disguised as letters, hidden in canned foods or in other covert ways.

"We are putting in all-out efforts into cracking down on narcotics using various investigative methods, such as inspection, communications tracking, big data analysis and digital forensics," the customs office said, noting that it will beef up border control to root out drug trafficking into Korea. (Yonhap)