Attorney-General Christian Porter said the money laundering breaches levelled against Westpac are "off the charts" and indicated that the bank can expect a fine well over the $700 million slapped on Commonwealth Bank for similar offences.

Mr Porter, who would approve any settlement, said the "unbelievably serious" allegations of millions of money laundering compliance breaches, some related to financing child pornography and exploitation, were of "enormous concern" to the Morrison government.