Commonwealth Bank, the country’s largest lender, has split with its major rival ANZ and backed the prudential regulator’s lending standards, suggesting critics of the conservative credit rules are looking for easy but ineffective ways to turn around falling rates of homeownership.

Matt Comyn, CBA’s chief executive, said there was little doubt that the buffer reduced borrowing capacity, but he argued it reduced financial risks. He said the Australian Prudential Regulation Authority was thinking about the rules – which force banks to evaluate the borrowing capacity of a customer by adding 3 per cent to the advertised rate – “in the right way”.