Nigeria's apex bank on Monday said it is working in collaboration with law enforcement agencies in investigating certain questionable financial transactions in some commercial banks in the country.

Spokesperson for the Central Bank of Nigeria Issac Okorafor said in a statement reaching Xinhua that the bank is carrying out its own special examinations and investigations to ascertain the veracity of some allegations, as well as the persons that maybe involved in such activities.

He said some of these investigations are routine and only relate to isolated transactions.

"It is important to state that the safety and soundness of the Nigerian Banking Industry remains strong," he added.

"The bank will like to reiterate that financial system stability remains a priority and therefore assures customers and stakeholders that it will not allow the banking system to be used as a conduit for any illicit transaction," Okorafor said.

Nigeria's Economic and Financial Crimes Commission is currently investigating the Managing Directors of Fidelity, Sterling and Access banks over some transactions allegedly made by former Minister of Petroleum Resources, Diezani Alison-Madueke.