A United Nations task force has terminated an investigation into allegations that North Korean agents abducted Japanese in the 1970s and 1980s, a support group for relatives of the missing said Saturday.

The Working Group on Enforced or Involuntary Disappearances, a unit of the Geneva-based U.N. Human Rights Commission, notified the relatives of the decision as of Jan. 30, stunning them. Their pleas led the panel to launch the investigation last year.

The panel said it ended the probe because it has not obtained sufficient information from North Korea, according to the support group, the National Association for the Rescue of Japanese Kidnapped by North Korea.

In March last year, the relatives of nine Japanese nationals suspected of being abducted by North Korea asked the Office of the U.N. High Commissioner for Human Rights to help achieve an early solution to the cases.

After the office promised to study the allegations at the working group, the relatives submitted a report on the cases to the panel in April.

Based on the report, the panel opened the investigation, including inquiries in North Korea.

Japan maintains that at least 10 Japanese were abducted by North Korean agents in seven incidents in the 1970s and 1980s. Pyongyang denies the allegations, but promised to search for the Japanese as "missing persons."

North Korea, however, said in December that it has terminated the search efforts.

The abduction issue is one of the biggest stumbling blocks to the normalization of ties between North Korea and Japan.