A Japanese fact-finding team left for North Korea Friday to gather information about Japanese citizens who were abducted by Pyongyang in the 1970s and 1980s.
Japanese Prime Minister Junichiro Koizumi also assured the victims' families that the government firmly supports them.
Japan's fact-finding mission will try to confirm the identities of more than a dozen Japanese people who were abducted decades ago.
In some cases they will attempt to use DNA evidence to prove whether the four abductees said to be alive are who Pyongyang claims. The team also will try to confirm how the other eight died.
Government spokesman Yasuo Fukuda said Friday the abduction issue is important because it concerns the safety and lives of the Japanese people. He adds the government will continue to try to seek the truth.
At a historic meeting with the Japanese prime minister last week, North Korean leader Kim Jong Il admitted that agents from his country had kidnapped at least a dozen Japanese citizens. They were taken to teach North Korean spies the Japanese language and customs.
Mr. Kim apologized and promised full disclosure on the fate of the victims. However, North Korea has yet to provide details on how eight of them died. So far, it attributes the cause of death to disease and natural disasters. The news of the deaths has sparked outrage across Japan.
Relatives have angrily demanded the North give further information as well as proof of the identities of the dead. At a meeting with Prime Minister Koizumi Friday, the families demanded that the surviving four be returned to Japan within a month.
At the meeting, the prime minister told them the government was strongly behind them. He said that officials are doing everything possible to reunite them with the four living kidnapping victims and to confirm how the others perished.
Tokyo on Friday dismissed a report carried by North Korea's state-run news agency describing Japan's anger at the abductions as "disproportionate furor".
Mr. Koizumi says the report will not affect Japan's policy of trying to learn more about the kidnappings.
North Korea and Japan have never set up diplomatic relations and ties have often been tense because of the abduction issue and historical disagreements. After the recent summit, the two sides scheduled a new round of normalization talks for October.