Police have discovered bank accounts in Japan that might have been part of an underground bank for the al-Qaeda network, investigative sources said Thursday.

The accounts were uncovered as part of an ongoing investigation into the activities of a Frenchman believed to be a senior operative of the Islamic terrorist network.

Deposits worth some 1 billion yen have been credited in the past three years to the bank accounts of two mobile phone sales companies run by Islam Mohamed Himu, a Bangladeshi man arrested Wednesday in connection with a probe into 33-year-old Lionel Dumont, who is thought to have been trying build an al-Qaeda base in Japan, the sources said.