Nigeria's anti-corruption agency has arrested six senior central bank officials over an alleged $30m (£20m) currency fraud.
The Economic and Financial Crimes Commission (EFCC) also held 16 private bank workers for the "mega scam".
The suspects stole "tonnes of defaced naira notes", which were meant to be destroyed, it said on its website.
Newly-installed Nigerian President Muhammudu Buhari has pledged to make tackling corruption a priority.
The suspects allegedly filled boxes supposed to contain damaged currency with bits of newspaper cut into the shape of naira notes, before sending them to branches of the Central Bank of Nigeria for destruction, according to the EFCC.
The actual banknotes were held back so that they could be reused, it adds.
The EFCC said the fraud had contributed to the failure of the government's policy of reducing inflation in recent years.