The RBNZ has published opinions from three international banking and finance experts who support the proposals.
Dr James Cummings of Sydney University, Professor Ross Levine of the University of California, and Professor David Miles of Imperial College, London, have "signalled their support with the direction in the capital review", said RBNZ deputy governor Geoff Bascand.
Cummings said the proposals were based on "sensible analysis", while Levine said the RBNZ analysis is "balanced".
Miles said "rather than being based on a view of risk that is excessively risk-averse, the analysis is closer to risk neutrality".
The RBNZ proposals, if introduced in their current form, will force banks to hold more capital aside as a safety buffer. Estimates suggest banks will need to raise more than $20 billion.
The rules would come into effect in April 2020, with a transition period of several years.
Banks have hit out at the plans and say they will be forced to increase interest rates on home loans and other products.
The RBNZ is doubling down behind the proposals.
Bascand said the independent experts "all acknowledged the quality of analysis underpinning our proposals, the transparency of our process, and the care we have taken to consider the points raised by submitters during the consultation process to date”.
The plans are in a consultation period, with responses and final decisions published in the first week of December.