Investigative sources say a man who claimed to be a long-wanted fugitive before dying in a hospital had hinted he was involved in a bomb attack, different from the one he had been wanted for.

Kirishima Satoshi was a member of the East Asia Anti-Japan Armed Front. The group is held responsible for 12 bomb attacks in 1974 and 1975, targeting companies doing business overseas.

Kirishima was placed on a nationwide wanted list on suspicion of his involvement in the bombing of a building in Tokyo's Ginza district in April 1975.

Police learned on Thursday last week that a man claiming to be Kirishima was hospitalized in Kanagawa Prefecture, near Tokyo. The man died on Monday.

The man reportedly denied involvement in the Ginza attack, but hinted he took part in another attack which was the 1975 bombing of construction company Hazama Corporation.

When investigators asked him what he thought of the bomb attacks carried out by the extremist group, he reportedly expressed regret.

Police are planning DNA tests to determine the man's identity, while analyzing what he told investigators.