A French national believed to be a senior member of al-Qaeda entered Japan on a fake passport in July 2002, traveled abroad frequently, and made the city of Niigata his hideout for more than a year while he was being hunted by Interpol, according to investigative sources.

The latest revelation about Lionel Dumont — who was arrested in Germany in December — has come as a shock to authorities in Japan because his arrival here coincided with stepped-up immigration controls following the Sept. 11, 2001, terrorist attacks on the United States.

It is the first time that Japanese authorities have uncovered evidence of a network in Japan centered around a senior member of al-Qaeda. The United States blames the network, led by Saudi-born terrorist Osama bin Laden, for the Sept. 11 attacks.