The corporate regulator agreed to alter a media release about a significant system error at National Australia Bank after it gave the bank the chance to "review" and suggest changes to the document before it was made public.

Internal documents from NAB's Wealth division, passed to Fairfax Media by a bank whistleblower, show that the Australian Securities and Investments Commission gave the bank the "opportunity" to review an ASIC media release the day before it was made public in May last year – and changed content in the release based on NAB's "feedback".

Illustration: Matt Golding.

The ASIC media release, issued on May 2, related to a significant, four-year-long "system error" in NAB Wealth's Navigator platform that had affected tens of thousands of customers. The release said that, after paying customers $1.9 million, a review had found that NAB would need to pay an addition amount of compensation.

In the media release, ASIC acknowledged the "co-operative approach taken by NAB Wealth in this matter".