Austrac last night declined to comment on whether National Australia Bank might be the next big financial institution to face legal action over possible non-compliance with anti-money laundering laws.On page 108 of its 2017 annual report published on Tuesday, NAB's directors revealed that the bank was remediating "issues" and "weaknesses" identified by internal audits of its anti-money laundering systems.The bank cannot say what the outcomes of these audits might be, but has confirmed that matters of concern to the bank's senior management have been reported to Austrac.Nor has NAB given much detail on what the compliance problems are, other than to say that they relate to Know Your Customer requirements and transaction monitoring.The compliance problems identified in the 12 months to the end of September were sufficiently important for the bank's directors to disclose an unquantifiable contingent liability in the company's latest financial accounts.While Austrac did not respond publicly to the disclosure, comments attributable to NAB's chief risk officer David Gall were emailed to media outlets on Wednesday afternoon.Here is what Gall said in the emailed statement:"NAB takes anti-money laundering obligations extremely seriously."We share Austrac's commitment, and recognise the important role we play in monitoring and reporting suspicious activity to AUSTRAC and keeping Australia's financial system safe."We have anti-money laundering policies and processes in place, and if we find weaknesses in these, we work hard to strengthen and fix them immediately. "As part of our strong and co-operative working relationship with Austrac, we regularly discuss how we can improve our processes to ensure people with bad intentions are prevented from committing crimes.  "In our annual reporting material, NAB has taken a transparent approach by disclosing our commitment to strengthening our processes and systems given the heightened market interest around these issues. "Austrac has said publically (sic) that NAB does not have compliance issues in respect of its smart ATMs, which have a deposit limit of $5000."While Gall's comments address aspects of the disclosures made by the bank in the annual report, they do not explain why NAB directors believe the "issues" and "weaknesses" warranted a contingent liability to be included in the accounts.NAB chairman Ken Henry and managing director Andrew Thorburn might have each forgotten to explain the contingency in their respective reports to shareholders in the annual report.However, activist shareholders will probably want more detail on the potential legal risks facing NAB at the annual meeting in Sydney on 15 December.Thorburn's next appearance at the House of Representatives economics committee might also be noteworthy, given that the NAB chief last month did not disclose the known weaknesses of the bank's anti-money laundering systems in answers he gave to questions from parliamentarians.