National Australia Bank CEO Andrew Thorburn says the problems with one of its home loan programs are regrettable and unacceptable.
Mr Thorburn says the bank has made extensive changes to its 'Introducer Program', which will be the first case study examined by the financial services royal commission.
"While many of the details of this issue are already known, the focus of the royal commission will again demonstrate that what occurred is regrettable and unacceptable," Mr Thorburn said ahead of Tuesday's public hearing.
NAB in November revealed about 2300 home loans may have been issued without accurate information or documentation since 2013.
Twenty bankers were sacked or resigned and another 32 were reprimanded over the issues connected to the introducer program, where NAB pays commissions to accountants and financial planners for successful lending referrals.
The problems were identified in 2015 through NAB's whistleblower program.
Mr Thorburn said none of the issues are acceptable.
"They should not have happened in the first place, and they show that we haven't always done right by our customers or treated the community with respect. This is not good enough.
"It's important now for us to move forward by learning from the past, owning up to mistakes and fixing them - and importantly, making sure they never happen again."