North Korea officials have presented to the international media a man they allege is a South Korean spy who tried to enter the North to kidnap children.
During a Pyongyang news conference detainee Ko Hyon Chol said he apologised for a crime he called "unforgivable".
Ko, 53, said he was born in North Korea but fled the country in early 2013 to resettle in the South.
He said he was later recruited by South Korea's spy service for a mission to abduct children from the North.
He said he was arrested on May 27 on an island in the Amnok River which runs along the border between North Korea and China.
North Korea often arranges news conferences for foreign detainees during which they read statements to acknowledge their wrongdoing and praise the North's political system.
Many detainees have said after their releases that they were coached or coerced on what to say.
Seoul's Unification Ministry quickly criticised North Korea for using a South Korean citizen for what it calls propaganda and demanded his release. The National Intelligence Service, South Korea's main spy agency, said it has no relations with Ko's case.
