Two daughters of Aum Shinrikyo founder Shoko Asahara and his lawyers are suing the government and a psychiatrist to fight the Tokyo High Court's dismissal of his appeal of the death sentence, the lawyers said Saturday.

The daughters filed the suit with the Tokyo District Court on Tuesday, seeking 50 million yen in damages.

The high court turned down the appeal last month, saying Asahara, 51, is mentally competent and that the defense team failed to present his case for appeal.

The court made the decision based on an assessment by psychiatrist Akira Nishiyama. The daughters and lawyers claim the high court "suddenly" rejected the appeal -- a day before the lawyers were planning to present their case -- to block their submission of the necessary documents.

Pointing out Nishiyama interviewed Asahara "only three times," the plaintiffs claim he had made up his mind beforehand to find the cult founder competent.

Nishiyama declined to comment on the suit. Asahara, whose real name is Chizuo Matsumoto, was sentenced to death by the district court in 2004 for his role in 13 criminal cases, including the 1995 sarin gas attacks on the Tokyo subway system that killed 12 people and injured more than 5,500.