The Tokyo High Court on Thursday upheld the death sentence of an Aum Shinrikyo chemist who produced the sarin used in two of the cult's deadly nerve gas attacks.

In upholding the lower court verdict, presiding Judge Osamu Ikeda condemned Seiichi Endo, 46, for utilizing his virology expertise to create the nerve agent used in the terrorist attacks, including the 1995 attack on the Tokyo subway system that shocked the nation.

"The accused played a vital role in manufacturing sarin, which was used on the subways. He bears the same criminal responsibility as those who carried out the attacks," the judge said.