Japan plans to file what it calls a "strong" protest with North Korea over Pyongyang's probe into the kidnapping of Japanese nationals by the Stalinist state decades ago.

The move was announced today (Friday) at a meeting between government officials and family members of kidnap victims.

Japan's Chief Cabinet Secretary Hiroyuki Hosoda warned of serious action if North Korea does not respond to its protest. He did not elaborate, but there have been growing calls in Japan for economic sanctions on North Korea over the abduction issue.

Japan has demanded North Korea provide information on eight kidnap victims from the 1970s and 1980s who Pyongyang says have died, as well as two more whose status is unclear. Tokyo says recent evidence provided by North Korea was false.