Members of a drug ring engaged in the production and distribution of methamphetamine derived from off-the-shelf cold medicine have been arrested, police authorities said.

According to Jeju Provincial Police on Thursday, two individuals, both in their 50s, were sent to the prosecution Wednesday on charges of violating the Narcotics Control Act. The accused include a man responsible for manufacturing the drug and his accomplice.

Both men are suspected of manufacturing a total of 20 grams of methamphetamine on more than 10 occasions from August last year to July in a rooftop room located in Gyeonggi Province. They are also alleged to have engaged in the illicit sale and distribution of the substance, and to have consumed it themselves.

According to the Jeju police, the inquiry was initiated with the voluntary confession of a 50-year-old drug buyer who wished to overcome drug addiction. The buyer, who confessed to have received and administered the drug from the ring, was referred to the prosecution without detention.

According to local media reports, the drug ring extracted meth ingredients by combining chemicals with cold medicines purchased at pharmacies, conducting their operations exclusively at night due to the strong ammonia smell produced during manufacturing.

The drug maker gained knowledge of drug production from overseas websites and began the criminal activity with the intent of self-administration.

Some 20 syringes, 2,460 over-the-counter drugs, 34 chemicals of six different types and 89 manufacturing instruments have been confiscated, the police said.