Exports of lamb were up to all major markets, including China and the European Union.
Today's merchandise trade data showed beef exports were up $16m (4.5 per cent) to $359m, with more exports to China. This increase was partly offset by a fall to the United States.
Overall exports were up $509m (10 per cent) to $5.4 billion, with meat exports having the largest increase. This exports total is the second highest for any month.
The highest exports total was $5.5 billion in December 2017.
Forestry products had the second-largest increase in exports, up $99m (26 per cent) to $477m. The largest increases were to China, Singapore, and Hong Kong.
On the other side of the ledger, motor vehicles led a rise imports over the month.
The value of total imports rose $277m (5.7 percent) in May 2018 to reach $5.1 billion, as New Zealand imported more cars.
Imports of cars rose $78m (17 per cent) in May. This boosted overall imports of vehicles, parts and accessories to $924m, up $185m compared with the same month last year.
In contrast, petroleum and products imports fell $196m (30 per cent) to $455 million in May 2018. Crude oil led this fall, down $256m to $68m.
The department noted that a maintenance shutdown at the Marsden Point oil refinery went into full swing from May 7. This work is scheduled to be completed in mid-June.
-- Staff Reporter