Lower exports of goods and services saw the country's current account deficit hit $2.8 billion in the first three months of the year, taking it to an annual level of 4.8% of GDP.

The deterioration, although not unexpected, is greater than anticipated by most economists - the median forecast was for an increase of about $1.4 billion over the quarter.

The figure is also important because New Zealand's long-standing current account deficit is regarded as the country's main long-term economic liability.

The most recent international assessments, from ratings agencies and from institutions such as the OECD, have pointed to the current account deficit as New Zealand's largest vulnerability.

The quarterly balance on goods and services has moved into deficit for the first time since December 2008, which is one of the main drivers of the drop, says Statistics New Zealand in its figures release today.

On an annual basis, the goods balance is still in surplus, by $2.7 billion, down $0.7 billion on the previous year.

This is due largely to the drop in dairy prices, along with a fall in the volume of crude oil exports.

On the tourism-dominated services sector, the fall is mostly caused by a drop-off after the Rugby World Cup-related increase in the previous two quarters.

However, the tourism balance has also fallen because New Zealanders are spending more abroad - travellers overseas spent $1.166 million in March, the highest quarterly level ever.

The country's net liabilities have actually shrunk to $143.2 billion, or 70.9% of GDP, down from $146.3 billion.

This because of a change in value of New Zealand's assets held overseas, and also the high kiwi dollar.