TOKYO (AFP) - A Japanese delegation is to arrive in North Korea on Monday for talks centred on Pyongyang's investigation into the Cold War kidnappings of Japanese citizens, which has marred relations for years.

The four-day visit - the first official Japanese delegation to the North in a decade - comes after Tokyo eased sanctions against the secretive state in July when it pledged to revisit the abductions in the 1970s and 1980s by North Korean agents.

Mr Junichi Ihara, who heads the Foreign Ministry's Asian and Oceania Affairs Bureau, is leading a group that will also include police and other experts.

"We plan to use this visit to Pyongyang to tell the person in charge that Japan regards the abduction issue as a priority," Chief Cabinet Secretary Yoshihide Suga, the government's top spokesman, told a regular press briefing in Tokyo on Monday. "We want them to explain the status of the investigation. At this meeting, we will call on them to carry out the probe swiftly and be sincere in their response to Japan."

Tokyo believes dozens of people were snatched to train the North's spies in Japanese language and customs.

North Korea admitted in 2002 that it had kidnapped 13 Japanese citizens to train its spies.

Five of the abductees returned home, but Pyongyang said - without producing credible evidence - that the eight others had died.

That claim provoked uproar in Japan, where there are suspicions that the actual number of abductees could reach into the hundreds.

Japanese officials had expected a report on details of the probe around September, but North Korea recently said it would be unable to supply substantial information in that timeline.

Tokyo and Pyongyang have no formal diplomatic ties, partially because of what Japan says is the North's unwillingness to come clean over the issue.