A global surplus supply of milk continues to keep New Zealand's income from dairy exports low.

The latest global dairy auction has seen prices fall overall by 1.4 percent after two previous rises - butter and milk have led the slump.

The price of whole milk powder rose point 7 percent.

ASB Rural Economist Nathan Penny said they were expecting a rise of whole milk powder of three to four percent.

"We've got high production in Europe, and that's taking it's time to slow - as well here in New Zealand while we've had a weaker season, previous seasons have had very strong production, so there's a lot of milk around and dairy buyers are spoilt for choice, and as a result prices remain low."

Mr Penny said it's a small drop and they still expect prices to gradually increase this year, to reach six dollars by the end of next season.