North Korea has presented to media a person it calls a South Korean spy who tried to enter the North to kidnap children.

Detainee Ko Hyon Chol told a news conference in Pyongyang on Friday that he apologized for a crime he called "unforgivable."

He says he is a North Korean defector who now works for Seoul's spy agency. He says he was arrested on May 27.

North Korea often arranges news conferences for foreign detainees during which they read statements to acknowledge their wrongdoing and praise the North's system. Many detainees have said after their releases that they were coached or coerced on what to say.

Seoul's Unification Ministry quickly urged North Korea to release Ko. Seoul's National Intelligence Service says it has no relations with Ko's case.