The affected banks are Citibank, Diamond Bank, Stanbic IBTC Nigeria and Standard Chartered Bank.
Commenting on the sanction in a statement released on Thursday, MTN said the sanctions damage investor confidence.
“The re-emergence of these issues is regrettable as it damages investor confidence and, by extension, inhibits the growth and development of the Nigerian economy,” it said.
“We will engage with the relevant authorities and vigorously defend our position on this matter and provide further information when available.”
Stanbic IBTC has also released a statement assuring customers of stability in its operations.
“The bank is holding further engagements with the CBN, in relation to the issues it has raised,” it said.
“Please be assured that the above does not impact on your ability to continue to conduct your various business and corporate transactions with Stanbic IBTC Holdings or any of its subsidiaries, including the bank.”