Korea's foreign ministry is looking into alleged cases of North Korean coal being shipped to the South via Russia last year.

According to an annual UN sanctions committee report, coal moved to the Russian port of Kholmsk was unloaded and reloaded on to two ships that then called at Incheon and Pohang in October, the Korea Herald reported.

North Korean cargoes were carried from Wonsan and Chongjin to Kholmsk between July and September last year on six occasions.