The scandal deepened further when comments allegedly made by chief executive Brian Hartzer to senior staff were leaked to The Australian, including claims the scandal "was not playing out as a high street issue" and that the Westpac board "don't need to overcook this" because "for people in mainstream Australia going about their daily lives, this is not a major issue".
Now, the Australian Prudential Regulation Authority (APRA) – the banking regulator – has ordered Westpac to set aside an additional A$500 million ($520m) in capital as an investigation gets under way that could end in hefty fines or the disciplinary action of high-ranking staffers.
APRA is looking into whether Westpac breached the Banking Act – including the Banking Executive Accountability Regime (BEAR) – and will examine its conduct in the lead-up to the Austrac allegations as well as its efforts to fix the problems after they were uncovered.
In a statement, Westpac confirmed it would co-operate with APRA.
"Westpac accepts the gravity of the issues presented by Austrac," Westpac Group's chairman Lindsay Maxsted said today.
"As previously stated, these shortcomings are unacceptable and we are determined to urgently fix these issues and lift our standards.
"We will provide our full support to APRA through its investigation and review."
Meanwhile, APRA deputy chair John Lonsdale said Austrac's statement of claim contained "serious allegations" that "question the prudential standing of Australia's second largest bank".
"While Westpac is financially sound, there are potentially substantial gaps in risk governance that need to be closed," he said.
"Given the nature of the matters raised by Austrac, the number of alleged breaches and the period of time over which they occurred, this will necessarily be an extensive and potentially lengthy investigation."
APRA has vowed to impose that increase in capital requirements of A$500m "to reflect the heightened operational risk profile of the bank", which brings the total operational risk capital add-ons that Westpac is required to hold to A$1 billion.
It will also launch an "extensive review programme" focused on Westpac's risk governance which will include risk management, accountability, remuneration and culture.
APRA's investigation will coincide with one being carried out by the Australian Securities and Investments Commission (ASIC), as well as Austrac's legal proceedings.