A Japanese man awaiting execution on China's death row has said a male Japanese acquaintance of his was involved in shooting and killing three women on July 30, 1995, at a supermarket in Hachioji, Tokyo, investigative sources said.

Japanese investigators are asking the Chinese side to allow them to interrogate the 66-year-old man, the sources said.

If approved, they will visit China before the statute of limitations for the murders expires within a year.

The three victims — two high school students aged 16 and 17 and a 47-year-old part-time employee — were shot in the head and face in the supermarket's office.

The man, who was sentenced to death for drug smuggling in August 2007 at a local court, told other acquaintances before he was arrested that the Japanese man was involved in the murders, according to the sources.

He is believed to have headed a group of Japanese and Chinese gangsters.