International factors are driving up the cost of food in New Zealand

Stats NZ says food prices rose 3.7 percent in the year to April, up from 3.5 percent to the month before.

There were large hikes in cheese, milk and especially butter.

ASB Senior Economist Mark Smith says New Zealand is following the rest of the world with a bit of a lag.

He says food commodity prices are quite strong across a range of products including dairy, meat and fruit and that's flowed through to retail.