AUSTRAC has accused Westpac of failing to report more than 19.5 million international funds transfer instructions to it over a period of five years, for money moving into and out of Australia.
The bank is alleged to have breached the Anti-Money Laundering and Counter-Terrorism Financing Act on more than 23 million occasions.
The anti-money laundering regulator says that Westpac failed to "carry out appropriate customer due diligence on transactions to the Philippines and South-East Asia, that have known financial indicators relating to potential child exploitation risks".