Reserve Bank governor Adrian Orr says he's not surprised, but has not been impressed with, the level of opposition he is seeing to proposed changes to bank capital ratios.

Speaking at a media lunch hosted by health insurer nib, Orr outlined the Reserve Bank's motivation for seeking to lift bank capital requirements and discussed the difficulties of engaging the broader public in what is seen as a complex issue.

The Reserve Bank is proposing a lift in the amount of risk weighted capital retail banks hold, from 8.5 per cent to 16 per cent.

The proposed increase is designed to