Offshore payments from a Westpac account at the centre of a multimillion-dollar fraud involving notorious conman Peter Foster have exposed another possible weakness in the major bank's risk monitoring systems.

Private investigator Ken Gamble and Sydney law firm Nelson McKinnon are investigating whether 39 payments totalling more than $8 million sent from a Westpac bank account to Hong Kong could be part of the 23 million transactions AUSTRAC alleges the bank failed to properly vet.

The Age and The Sydney Morning Herald do not allege Westpac failed to report these transactions to the AUSTRAC and the payments were not referenced in the financial intelligence agency's statement of claim against the bank.

There are no allegations regarding those transactions, and 'tipping off' laws mean that Westpac cannot comment on whether SMRs [suspicious matter reports] were filed in relation to any customer," Westpac said in a statement.

The Hong Kong payments have come to light as Westpac's international transfers and risk management systems are under increased scrutiny. AUSTRAC's landmark lawsuit against the nation's oldest bank last month prompted the resignation of former chief executive Brian Hartzer and will lead to the early departure of chairman Linsday Maxsted next year.

If AUSTRAC was not alerted to the Hong Kong payments, Mr Gamble said he would seek to take legal action against the bank directly. AUSTRAC said it would not be appropriate to comment on the payments.

The payments came to light following a judgment handed down in the NSW Supreme Court in late November that found Sydney lawyer Leigh Johnson was a signatory to the Westpac account. The court found Ms Johnson knew conman Mr Foster was involved in the scheme and was also aware he used a fake name and did not inform law enforcement.

The findings against Ms Johnson were made in the civil suit and were not criminal findings.