Japan said on Wednesday it believed that North Korea would go ahead with a new probe into the fate of Japanese abductees despite halting cooperation on denuclearisation.
North Korea said on Tuesday it would consider restoring its Yongbyon nuclear complex, accusing the United States of violating an agreement to remove it from a terrorism blacklist.
Japan had opposed the US decision to delist North Korea due to a long-running row over the hardline communist state's kidnappings of Japanese civilians in the 1970s and 1980s to train its spies.
Japan's government spokesman said that North Korea's latest announcement "has no direct link" with its promise in June to reinvestigate the fate of the kidnap victims.
"We hope that North Korea will set up a committee to resume the research, based on the agreements we have reached," said Nobutaka Machimura, the chief cabinet secretary.
He called on North Korea to reverse its decision on the denuclearisation drive, rebutting Pyongyang's argument that the United States was not living up to its side of the deal.
"It is actually North Korea that is going against the principle of an action for an action," Machimura told a news conference.
"We are hoping for a sincere response from North Korea," he said.
Japanese media have speculated that the United States is holding off on removing North Korea from the blacklist in hopes of triggering progress in the abduction feud.
North Korea admitted in 2002 to kidnapping 13 Japanese and released five of them, but said the others were dead.
The issue has roused deep emotion in Japan, which contends that North Korea may be keeping some victims under wraps.
Prime Minister Yasuo Fukuda is known as a moderate on North Korea and has faced opposition for agreeing to relax some of Japan's own sanctions on Pyongyang in exchange for the kidnapping probe.