Westpac says it has provided information on more than 500,000 additional transactions to Australia’s financial crime watchdog in relation to a money laundering and child exploitation scandal.

Australia’s second-biggest lender on Tuesday said not all of these transactions of $10,000 or more which it disclosed to The Australian Transaction Reports and Analysis Centre (AUSTRAC) may have breached anti-money laundering laws.

Westpac is facing allegations that it enabled more than 23 millions illegal payments, including between known child sex offenders, in a scandal that has resulted in a major management overhaul and the lender’s setting aside $900 million for a possible penalty.

Westpac said after looking deeper into its systems and in response to a notice from the AUSTRAC, it disclosed about 175,000 transactions it had not previously reported and another 365,000 for which it may not have had complete or accurate information.

“A significant proportion of the potential reporting issues relate to a range of complex scenarios where the legislation requires Westpac to exercise judgement on how multiple transactions may be aggregated and whether a threshold transaction has actually occurred,” the bank said in a statement.

The lender said it was still working with AUSTRAC and that the number of threshold transaction reports may change.