Specialized teams tasked with investigating drug-related crimes have been launched in four major cities.

The Supreme Prosecutors' Office(SPO) said the teams within district prosecutors' offices based in central Seoul, Incheon, Busan and Gwangju began investigations on Tuesday, four months after the government unveiled comprehensive crackdown measures on drug-related crimes.

The four teams will investigate large-scale drug trafficking, the illegal distribution of narcotic substances intended for medicinal purposes and online distribution through the dark web.

They will comprise a total of 84 officials from the prosecution, Korea Customs Service, the food and drug ministry and local governments as well as the Korea Internet and Security Agency, which plans to deploy an AI-based system within the year that constantly monitors online posts or websites linked to drug deals.

The SPO estimates that in 2021, the number of criminals charged with drug-related offenses climbed nearly 14 percent on-year to exceed 18-thousand.