South Korea's spy agency has confessed to kidnapping former president Kim Dae-jung in Tokyo while he was an opposition politician in 1973.
A report issued Wednesday said then-president Park Chung-hee had given at least his tacit approval.
The National Intelligence Services report was the agency's first acknowledgment of involvement in the incident.
The report did not draw a clear conclusion over whether its predecessor, the Korean Central Intelligence Agency, ultimately planned to kill Kim.
The NIS found Japan partly responsible for the kidnapping.
Japan's Chief Cabinet Secretary Nobutaka Machimura said the claim of Japanese responsibility is unacceptable.
Japanese Prime Minister Yasuo Fukuda expressed regret that South Korea violated Japan's sovereignty.
Kim Dae-jung narrowly lost to former general Park Chung-hee in 1971 elections.
After spending years in prison and exile, Kim was elected president in 1997. He was awarded the Nobel Peace Prize in 2000 for his efforts to improve ties with North Korea.
Some information for this report was provided by AFP, AP and Reuters.