Japan will not restart normalization negotiations with North Korea unless Pyongyang fulfills its promise to reinvestigate the cases of 10 missing Japanese nationals, the government's top spokesman said Monday.

Tokyo charges that the 10 were abducted by North Korean agents and believes some are still alive. In September 2002, North Korea explained that eight had died in the country and that it knew nothing of the other two.

During Saturday's summit between Prime Minister Junichiro Koizumi and North Korean leader Kim Jong Il, Kim promised to launch a fresh probe into the 10, in keeping with Japanese demands.