The Tokyo High Court on Thursday upheld a 20-year prison term for one of the most notorious members of the Japanese Red Army, saying she played an indispensable role in plotting and aiding the 1974 seizure of the French Embassy in The Hague.

But presiding Judge Fumio Yasuhiro dismissed prosecutors' claims that Fusako Shigenobu, 62, was one of the leading members of the guerrilla group at the time, noting the organization of the group had not been firmly established as of 1974.

Appealing a 2006 Tokyo District Court ruling, prosecutors had demanded that Shigenobu, also accused of passport forgery, be given a life term as one of the group's top leaders at the time of the attack.