A former member of a radical Japanese leftist group behind deadly bombings in the 1970s may finally have been caught after almost 50 years on the run, investigative sources said Friday.

Now 70, Satoshi Kirishima's youthful, bespectacled and long-haired mugshot has featured on "wanted" posters outside police stations across Japan for decades.

Police were still trying to confirm his identity, but on Thursday a man believed to be Kirishima was detained at a hospital in Kanagawa Prefecture.