New Zealand recorded its highest January deficit on record and the seasonally adjusted deficit was also more than double what economists had been expecting as a fall in exports outstripped their forecasts.

The January trade deficit was a seasonally adjusted $791 million, as exports fell 7.8 per cent on the year to $4.65 billion and imports lifted 0.4 per cent to $5.44b, Stats NZ said.

Economists had been expecting a $300m deficit in January, with exports tipped to be $4.8b and imports seen at $5.05b, according to a Bloomberg poll.

In actual terms, the deficit was $914m, surpassing the previous record of $894m in January 2006. Stats NZ noted, however, that as two-way goods trade has nearly doubled since then the January 2019 deficit is equal to 9.0 per cent of two-way trade compared with 17 per cent in 2006.

In actual terms imports rose 7.7 per cent to $5.3b while exports rose 3.0 per cent to $4.4b.

Catherine Beard is the executive director of Export New Zealand. She told Larry Williams it is a very difficult to forecast in the current market conditions.

"You have volatile commodities like Crude oil and diesel which go up and down a lot, which can make quite a bit of difference to the statistics."

Stats NZ said the increase in imports was spread across a range of commodities, with petroleum and products leading the rise – up $81m, or 13 per cent on the year.

The lift in exports, meanwhile, was led by milk powder, butter, and cheese – up $167m to $1.5b. Exports of milk powder, butter and cheese to China rose $9.1m from January 2018, to reach $200m.

The largest fall in exports was for meat and edible offal, down $66m in January 2019 from January 2018. Lamb exports were down $26m, while beef exports fell $28m.

Exports of lamb to the EU were at their lowest January value since 2006, it said.

The annual deficit was $6.36b versus an annual deficit of $6.11b in the prior year. Economists had expected a deficit of $5.5b, according to the poll.