Bank of New Zealand's mortgage book grew by a net $455 million in the three months to March.
Earlier this month, chief executive Andrew Thorburn said BNZ is not part of the problem of risky mortgage lending currently preoccupying the Reserve Bank.
However, Radio New Zealand's business editor says a fair amount of its new lending is in that high-risk area.
BNZ, which is owned by National Australia Bank, lent $294 million in mortgages to people with deposits larger than 20% in the latest three months.
But it also lent $75 million to people with deposits between 10% and 20% and another $86 million to people with less than a 10% deposit.
The proportion of its mortgage lending to people with less than a 20% deposit rose from 14.4% of its total book in December to 14.8% in March.
That compares with 14% in March last year.
