Total imports in March rose $612 million, 14%, to $4.94billion, while exports were down 2.6% at $4.85billion, Statistics New Zealand international statistics manager Tehseen Islam said in a statement.
The gap produced an $86 million deficit for March, compared with the $275 million surplus the markets expected. ASB had predicted a $100 million surplus and Westpac a $350 million surplus.
ASB rural economist Nathan Penny said the March trade balance was weaker than expected and, in particular, fuel imports were stronger than expected.
"Specifically, petroleum and petroleum products import values spiked 40.5%," he said in a statement.
With Brent crude prices lifting 2.5% during the month, the remainder of the spike in values could be put down to a surge in import volumes, Mr Penny said.
Westpac senior economist Michael Gordon said the trade balance slipped into the red in March, against Westpac’s forecast of a $350 million surplus. The annual deficit widened to $3.4billion, its highest since June last year.
Mr Islam said the rise in March imports was mainly driven by imports of crude oil, petrol, diesel, aircraft, computers and tractors.
"The rise in crude oil imports for the March 2018 month came mainly from the United Arab Emirates and Malaysia ... while the rise in petrol and diesel imports came mainly from Korea," he said.
Petroleum products rose $297 million, or 88%, to $634 million, the largest increase since a $453 million rise in December 2013. Crude oil rose $198 million, while petrol and diesel rose $94 million in March.
The value of crude oil imports in March was the lowest since the February 2009 month, he said.
Milk powder, butter, and cheese led the rise in exports, rising $265 million, or 5.8%, to $4.9billion in March compared with a year ago.
Forestry products rose $70 million, or 18%, to $460 million, led by a rise in untreated logs to China, which was up $54 million, Mr Islam said.
