Customs officials found the unspecified devices Dec. 20 among freight containers received by a South Korean contractor, which is building a liquefied-gas factory near Korsakov.

Their radiation levels exceeded background radiation limits by 200 times, extending 12 feet around the container.

Officials at the state sanitary and epidemic-prevention agency told Novosti anyone closer than 12 feet would have been exposed to radiation.

Kim Jong Hon, president of South Korea's All Nations Co., was arrested on Sakhalin Island Wednesday and charged with trying to smuggle radioactive devices into Russia