The Australian Bankers' Assocation says New Zealand central bank reforms aimed at limiting IT offshoring by the country's biggest banks could cost the industry up to A$300 million in lost efficiencies.
The ABA issued the Boston Consulting Group opinion on the costs of reforms as part of its submission to the NZ Reserve Bank.
The document claims the draft policy would "affect the efficiency of the New Zealand banking system, limit the range and sophistication of the products and services offered, and increase prices to customers".
Australia's largest banks have been fighting a losing battle to change the Reserve Bank policy, which is aimed at ensuring that systemically important banks do not ousource key functions to overseas offices.
The Boston Consulting Group bases its estimates on losses from economies of scale, a higher cost of capital and slower development of products.
However, Massey University director of banking studies David Tripe told the New Zealand Herald that he found the BCG estimates to be massively over-inflated.
"The argument they put forward in relation to economies of scale bears no relationship to any academic literature that I'm aware of."