A total of 23 Thai nationals have been apprehended in a recent crackdown of a drug trafficking ring targeting migrant workers in South Korea, police said Wednesday.

Seventeen of them were drug traffickers and six were users, the Seoul Dongjak Police Station said.

All but three drug users have since been formally arrested, the police said.

The ring's head of drug distribution is suspected of having smuggled a total of 2.5 kilograms of methamphetamine from Thailand to South Korea via international shipping on four occasions between April and October.

The volume of the smuggled drugs, worth about 16 billion won ($13.5 million), was enough to be administered to 83,000 people at the same time, according to the police.

In the crackdown, the police seized 1.3 kg of meth and 685 tablets of yaba, a combination of meth and caffeine, as well as criminal proceeds of 97.2 million won.

The ring was found to have used social network services to mostly sell drugs to foreigners working across the country.

The police said they will work with Interpol and local authorities to investigate a person who was in charge of supplying the drugs from Thailand.

"We will further strengthen crackdowns on international drug trafficking in cooperation with the related authorities, including the Korea Customs Service," a police official said. (Yonhap)