Police said one Afghan, two Pakistanis, two Indians and four Koreans were detained for trying to use South Korea as a shipping point for several tons of acetic anhydride destined for southern Afghanistan. The chemical is heated with morphine, an opium derivative, to make heroin.

In cooperation with the international police organisation Interpol, South Korean police were also hunting three foreigners who had fled abroad, Oh Ki-Duk, an investigator said.

Police confiscated 12 tons of acetic anhydride in a chemical engineering factory in the Seoul suburb of Ansan and arrested two people including a 47-year-old suspected Taliban member, he said.

"The key Afghan suspect admitted he did it at the instigation of the Taliban," Oh said. "But he claimed he is not a member of the Taliban."

He said the suspect had tried to smuggle the chemical, disguised as motor oil, into Afghanistan through Iran. Oh said the Afghan came to South Korea on a forged passport and recruited Pakistani and Indian workers in the country. "Despite his denial, we have circumstantial evidence that he is a Taliban member," he said.

In a separate operation led by Pakistanis, police said about 50 tons of the chemical had already been shipped to Afghanistan between April last year and March this year. It was labelled as disinfectant.