At least 400 Nigerians who have been secretly financing terrorist group, Boko Haram have been arrested.

According to DailyTrust, the suspects were arrested in Kano, Borno, Abuja, Lagos, Sokoto, Adamawa, Kaduna and Zamfara.

In Kano, a major focus for the operation, traders at the foreign exchange open market in Wapa, Fagge Local Government, were picked up on March 9, 15th and 16th, the Daily Trust reported.

Over 900 people are being investigated by security agencies.

And among them are bureau de change operators, gold miners and sellers and businessmen.

The probe was sparked by the jailing of six Nigerians in the United Arab Emirates last year over allegations of terrorism financing.

The closely-guarded operation is being coordinated by Defence Intelligence Agency (DIA), in collaboration with the Department of State Services (DSS), Nigerian Financial Intelligence Unit (NFIU) and the Central Bank of Nigeria (CBN).

The inter-agency operation is being led by a top intelligence officer, with an army general leading a task team comprising military personnel and staff from intelligence services.

As part of the operation, billions of naira traced to businesses belonging to persons of interest have been blocked in banks in series of “post no debit” letters sent out to banks by the CBN and NFIU.

The apex bank has also lately obtained court orders directing freezing dozens of accounts flagged for suspicious transactions.

Four of the arrested BDC operators were related to two persons jailed in Dubai last year on similar charges.

Those arrested are being kept in military and DSS facilities in Abuja and other places, even as their families and lawyers decry the continued detention of the suspects without trial or informing them of their offences.