Members of the radical Japanese Red Army may launch a terrorist attack to liberate arrested leader Fusako Shigenobu, the National Police Agency warned in a report released Thursday.
The report said Japanese Red Army cadres are working to revive the weakened group and are looking for a new base of operations.
Fifty-five-year-old Shigenobu, the group's key figure in a series of international terrorist incidents in the 1970s, was arrested in Osaka Prefecture on Nov. 8 after nearly 30 years on the run.
Four other Japanese Red Army members have been arrested and are being held in Japan after they were expelled from Lebanon in March.
The NPA said the group has not given up its armed struggle, adding, "Six other members are still on the run, including ones who committed vicious crimes in the past."
The report also said the Aum Shinrikyo cult still poses a threat to society, reflected in its members' behaviors. Earlier this year, cult members abducted a son of Aum founder Shoko Asahara after declaring in January that it would never again break the law, police said.
Asahara, whose real name is Chizuo Matsumoto, is on trial in a number of criminal cases, including the 1995 sarin gas attack on the Tokyo subway system, which killed 12 people and injured thousands.
The cult, which has changed its name to Aleph, is now run by Fumihiro Joyu, the cult's former spokesman.