The Supreme Court has upheld a rightist group leader's life sentence for the 2002 murder of Democratic Party of Japan lawmaker Koki Ishii, sources said Wednesday.

The top court's No. 3 Petty Bench on Tuesday dismissed the appeal of Hakusui Ito, 51, who was convicted of fatally stabbing the 61-year-old House of Representatives member outside the lawmaker's home in Setagaya Ward, Tokyo, on Oct. 25, 2002.

The defendant had claimed he attacked Ishii because the lawmaker did not pay back a favor Ito did for him in raising funds. Ito's sentence by the Tokyo District Court was upheld by the Tokyo High Court.