Reserve Bank governor Alan Bollard has slashed interest rates, citing "unpleasant" international news and the risk the domestic economy will slow further, even as inflation heads to 5%.

The number of housing loans approved by banks each week has been dropping sharply, a new experimental Reserve Bank data series shows.

The apparently high level of riskier home loans shown in the government-owned Kiwibank's latest general disclosure statement (GDS) isn't a fair reflection of the quality of its mortgage portfolio, says managing director Sam Knowles.

The two New Zealand-owned home lending banks appear to have vastly different risk appetites.

New bank disclosure rules reveal ASB Bank's mortgage book is particularly conservative although there's also evidence the global credit crunch is starting to nibble.

While Reserve Bank governor Alan Bollard left interest rates unchanged as expected, his latest monetary policy statement sparked a huge rally in interest rate markets and the New Zealand dollar fell more than one US cent.

Most economists expect Reserve Bank governor Alan Bollard won't be quite ready to start cutting interest rates this week but a growing majority are expecting a rate cut by the end of September.

Reserve Bank governor Alan Bollard left interest rates unchanged as expected, acknowledging the weakening economy but saying short-term inflation pressures remain persistently high.

Nobody expects Reserve Bank governor Alan Bollard to change interest rates this week, despite the fast-weakening economy, because inflation pressures are still far too strong.

The Commonwealth Bank of Australia-owned ASB Bank's share of the mortgage market fell in the December quarter.

Kiwibank says its home loan book was affected by the slowing housing market but it still managed to increase market share in the December quarter and net profit for the three months was up 35% from the same quarter a year earlier.

Reserve Bank governor Alan Bollard left interest rates unchanged although his comments about upside risks to inflation pushed the currency and wholesale interest rates up.

Both Westpac and TSB Bank saw their shares of the mortgage market shrink slightly in the December quarter, although both reported strong profits.

With inflation a continuing problem, Reserve Bank governor Alan Bollard is likely to hold interest rates at current high levels, despite an increasingly uncertain outlook for world growth and drought dampening agricultural production.

Bank of New Zealand's share of the mortgage market was steady in the December quarter last year, although its profitability fell compared with the same quarter a year earlier.

ANZ National Bank's core net profit rose and its share of the mortgage market increased in the December quarter.