ANZ in New Zealand has been rebuked by the Reserve Bank, with the RBNZ on Friday announcing that it "revoked ANZ Bank New Zealand Limited's accreditation to model its own operational risk capital requirement due to a persistent failure in its controls and attestation process".ANZ NZ is now required to use the standardised approach for calculating appropriate operational risk capital. From March 2019, this will increase its minimum capital held for operational risk by around 60 per cent to NZ$760 million, the RBNZ said.ANZ NZ in fact alluded to this embarrassing turn of events two weeks ago in its disclosure statement for the six months to March 2019.The bank wrote in that document that "in April 2019, the bank informed RBNZ that in the course of a self-review, the bank discovered that it had not been using an approved model for the calculation of the operational risk capital requirement since December 2014."The RBNZ made plain its annoyance on Friday."Accreditation is earned through maintaining high risk management standards, and comes with stringent responsibilities for the bank's directors and management," deputy governor Geoff Bascand said."The Reserve Bank's role is to review and approve internal models. The onus is then on bank directors to ensure, and attest, that their bank is compliant with the Reserve Bank's regulatory requirements. "To do that, bank directors need to be satisfied that the internal assurance processes that sit behind the attestations are being adhered to."ANZ's directors have attested to compliance despite the approved model not being used since 2014. The fact that this issue was not identified for so long highlights a persistent weakness with ANZ's assurance process."