Wellington  - The consumer price index increased 1.7 per cent in the year to September 2009, government agency Statistics New Zealand said Thursday.

The index measures the rate of price changes of goods and services purchased by households.

Most of the rise was due to an unexpectedly strong 1.3-per-cent increase in the September quarter, according to a Statistics New Zealand press statement.

The increase was the lowest in five and a half years.

The government agency attributed the low rise to a fall in petrol prices and airfares during the year, which partly offset higher prices for food, electricity and local authority rates.

Inflation figures for the December quarter are due to be released in mid-January. (dpa)