A sniffer dog searches for luggage containing hidden drugs during an event marking U.N.-designated International Day against Drug Abuse and Illicit Trafficking at Incheon International Airport, June 18. Yonhap

More than 700 kilograms of illegal drugs were seized at border checkpoints in Korea last year, representing a more than five-fold increase in drug smuggling attempts compared to 2020, data showed, Monday.

The data, compiled by the Korea Customs Service (KCS) and Incheon International Airport Corp. and released by Rep. Jeon Yong-gi of the main opposition Democratic Party of Korea (DPK), heightens concerns about the surge in narcotics trafficking in Korea, which was once considered a drug-free country.

A total of 769 kilograms of drugs, worth 61.3 billion won ($45.75 million), were confiscated at the airport and other gateways to Korea in 2023, according to the data.

The volume was approximately 5.1 times higher than in 2020 and also represents an 18 percent increase from 2022.

"The customs agency, together with the airport authorities, police and other relevant parties, should beef up monitoring of narcotics smuggling attempts at border checkpoints," the lawmaker said.

In 2023, 327 kilograms of drugs worth 25.1 billion won were smuggled into the country through international mail.

Another 275 kilograms, worth 19.9 billion won, were hidden in express cargo, while 148 kilograms, valued at 15.1 billion won, were carried by air travelers.

By type, methamphetamine accounted for 438 kilograms of all the drugs seized. Club drugs, such as ketamine, totaled 172 kilograms, while marijuana amounted to 143 kilograms, and cocaine constituted 11 kilograms.

In terms of sales value, methamphetamine was worth 40.8 billion won, followed by club drugs at 9.2 billion won, marijuana at 7.2 billion won, and cocaine at 3.9 billion won.

Of the KCS' regional offices, Incheon Airport Regional Customs confiscated 649 kilograms, accounting for 87 percent of the total amount of drugs traffickers attempted to bring into Korea last year.

The Busan office seized 46 kilograms of drugs, while the Gwangju office confiscated 28 kilograms.

The data comes as Korea is no longer considered a drug-free country and the government is stepping up crackdowns on narcotics traffickers and offenders.

The U.N. Office on Drugs and Crime defines a country as drug-free if the number of substance abusers is below 20 per 100,000 people.

Korea surpassed this number in 2016 when it reached 25. The number has been on the rise since and hit 35 in 2023.

In the first half of this year, the KCS reported 362 attempted drug smuggling cases.

The figure was up 11 percent from the first six months of 2023. The data also suggested that, on average, there were two smuggling attempts per day.