Radio New Zealand

Dairy prices have fallen by 2.4% at Fonterra's online auction.

The dairy cooperative's Global Dairy Trade-Weighted Price Index fell to an average selling price of $US2843 dollars a metric tonne at the auction overnight on Tuesday.

Cheddar and lactose prices rose, offsetting a 13% fall in milk fat prices.

Two weeks ago prices slumped by 10% - the biggest decline since July 2010.