The Reserve Bank of New Zealand has issued a formal warning to Kiwibank for failing to carry out full due diligence under rules aimed at countering money laundering and the financing of terrorism.Kiwibank said the warning related to requirements for existing customers to upgrade their identification details and the verification of the sources of funds for some high risk customers."Kiwibank accepts that it did not meet some of the requirements during the period and has taken steps to remedy the issues identified," Kiwibank said.There was no mention of penalties or sanctions being applied against the bank.