In its annual report which was released this week, acknowledgment of the investigation was revealed deep within the document on page 108 where it noted "the group is currently investigating and remediating a number of identified issues".
While it is believed NAB has not breached compliance issues with the financial intelligence regulator, the Australian Transaction Reports and Analysis Centre (AUSTRAC), the bank says its systems may require "additional strengthening".
"The group is currently investigating and remediating a number of identified issues, including certain weaknesses with the implementation of 'Know Your Customer' requirements and systems and process issues that impacted transaction monitoring and reporting for some specific areas," NAB says in its report.
"It is possible that, as the work progresses, further issues may be identified and additional strengthening may be required.
"The outcomes of the investigation and remediation process for specific issues identified to date, and for any issues identified in the future, are uncertain."
The revelations follow explosive allegations made by AUSTRAC against rival bank CBA that it failed to notify it of more than 53,000 transactions at its network of so-called 'intelligent' automated cash deposit machines (IDMs), with a total transaction value of $624 million.
IDMs can accept up to 200 notes per deposit or up to $20,000 per cash transaction with no limit on the number of transactions per day and it's alleged the breaches occurred unchecked for three years between 2012 and 2015.
Last month NAB chief executive Andrew Thorburn did not mention his company's potential anti-money laundering issues when he fronted the House of Representatives economic committee, which was grilling bank bosses on the subject in the wake of the CBA legal action.
Thorburn told the committee that NAB took its anti-money laundering responsibilities very seriously and was committed to improving its compliance systems.
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