The bank said it had found around 2,300 home loans since 2013 that "may not have been established in accordance with NAB's policies," after an extensive review.

"What occurred was unacceptable,” NAB Chief Customer Officer, Consumer Banking and Wealth, Andrew Hagger, said.

"We have investigated this matter thoroughly ... we have improved our systems, processes and programs as a result of what occurred here.”

A further 32 bankers had faced repercussions including pay cuts, NAB said.

The bank had been aware of the matter since October, 2015 and had been in touch with the banking regulator since December that year.

It would offer customers remediation that may include compensation.

NAB also said this week it had found weaknesses in systems that monitor customers as part of a program to comply with money-laundering and counter-terrorist financing laws, and flagged further problems could be discovered.

The Australian banking sector has been fending off calls for a powerful judicial inquiry amid accusations of widespread abuses at their financial advice and insurance units.

The Australian Securities and Investments Commission has taken NAB and two other of country's biggest lenders - Westpac Banking Corp (>> Westpac Banking Corp) and Australia and New Zealand Banking Group Ltd (>> Australia and New Zealand Banking Group) - to court, accusing them of rigging the bank bill swap reference rate (BBSW) for profit.

In August, the financial intelligence agency filed a lawsuit against Commonwealth Bank of Australia (>> Commonwealth Bank of Australia) for what it called "systemic" breaches of money laundering and terror-financing rules.

(Reporting by Melanie Burton)