The corporate regulator may take action against National Australia Bank over its "introducer" home loan fraud, despite some senior ASIC staff suggesting the bank be let off the hook.
The Australian Securities and Investments Commission has taken action against individuals over the fraud and misconduct by 60 bankers, including branch managers.
But ASIC only expanded its investigation to include the bank itself in the last couple of months, well after the banking royal commission examined the case in March.
"I'm clearly of the view that we need to be taking action against NAB," ASIC chair James Shipton said on Thursday.
An email shown at the royal commission showed some members of ASIC's enforcement committee did not share that view, with one effectively suggesting "doing nothing" as an option.
The July 2018 email showed the committee's chair thought an enforceable undertaking with a community donation would be enough, noting "what do we have to lose from doing this".
Mr Shipton said that view did not align with his thinking or ASIC's current practice of asking why not litigate.
"In my view, and I expressed this when the conversation was happening, we should be pursuing much harder, much tougher action and we ultimately did."
Senior counsel assisting the commission Rowena Orr QC said one view in the email was the antithesis of that, by suggesting there be no further investigation and an enforceable undertaking so ASIC could be seen to have publicly responded to the inquiry.
Sixty bankers were involved in fraud and misconduct connected to NAB's introducer program, which pays people outside the bank such as financial planners and accountants for successful lending referrals.
The inquiry previously heard several bankers created false documents and accepted cash payments from introducers, while some staff took bribes for fraudulent home loans with the money exchanged in white envelopes.
A NAB spokesperson said the bank was engaging with ASIC on issues related to the introducer program, including banker misconduct and customer remediation.
"We have made significant changes to the introducer program to address the underlying causes of the conduct and prevent similar issues from occurring again."
NAB began investigating issues with loans set up by bankers in western Sydney in 2015 following whistleblower complaints.
