Financial crime agents say they have arrested 21 bankers including senior executives of the Central Bank of Nigeria for the theft of $33 million worth of defaced naira currency notes.

The Economics and Financial Crimes Commission says a whistleblower alerted it to the "mega scam" that it believes has gone unchecked for years.

It says officers of eight commercial banks in Nigeria, including bank leaders Ecobank and Zenith Bank, are among the suspects.

The fraud involved replacing notes in Nigeria's naira currency that had been designated for destruction with cut up pieces of newspaper. It charges the suspects then recycled the defaced and mutilated notes.

A statement Monday says those arrested will be charged on five counts in a federal high court this week.