Japan has reportedly issued arrest warrants for two North Korean agents it says kidnapped Japanese nationals.
Some of the kidnapped Japanese were allowed home in 2002
Warrants have been issued for Shin Kwang-su and Choi Sung-chol, the reports said, although police only confirmed the warrant for Mr Shin.
The two men, who are believed to be in North Korea, are suspected of kidnapping four Japanese in 1978.
The North admitted in 2002 that it had abducted 13 Japanese to help train its agents as spies.
Five were allowed to return to Japan, while North Korea insists the other eight are dead. But Tokyo says Pyongyang has never provided conclusive proof of their deaths, and many Japanese suspect some of them may still be alive.
Tokyo says the issue must be resolved before the two countries can establish diplomatic ties.
Snatched in the '70s and '80s
Used as cultural trainers for N Korean spies
Five allowed home in 2002
Five children now freed from N Korea
Eight said to be dead, others missing
Bilateral talks held earlier this month made no progress on the issue.
At a news conference on Thursday, Chief Cabinet Secretary Shinzo Abe again urged North Korea to co-operate in resolving the abduction issue.
"I think it is necessary for the North Korean side to clear everything up," he said. "I ask that North Korea hand over these suspects to Japan."
Shin is suspected of having abducted Yasushi Chimura and Fukie Hamamoto in western Japan in July 1978, while Choe is thought to have abducted Kaoru Hasuike and Yukiko Okudo from northern Japan at about the same time.
After decades in Pyongyang, the two couples were finally allowed to return to Japan in October 2002.
Shin is also wanted in connection with the suspected abduction of another Japanese national, Tadaaki Hara, in 1980. Mr Hara's whereabouts are still unknown.
Mr Abe said that the Japanese government would ask the international police agency Interpol to list the two North Koreans on a wanted list.