Wellington, Aug 3 NZPA - Fonterra's milkpowder prices fell for the fourth consecutive month at today's online auction.

The average selling price of all products dropped to $US3080 ($NZ4199) a tonne, triggering an 8.3 percent drop in Fonterra's global dairy trade index.

Prices have been falling since a 21-month high at the April auction, when the average price for whole milkpowder was $US3969/tonne, compared to today's $US2974.

At the previous auction in July, the weighted index for a basket of products at the auction fell 13.7 percent. It dropped 3.5 percent in June after falling 0.8 percent in May.

Today, whole milkpowder (WMP) prices dropped 7.7 percent, while skim milkpowder (SMP) recorded an 8.9 percent drop.

But the biggest drop, 13.2 percent for all products, was in the shortest term contracts, for October delivery.

Contracts to deliver over the three months from November -- the height of the southern hemisphere dairy season, fell 8.6 percent, and contracts for the three months from February fell only 1.7 percent.

The next auction will be on September 1, when the internet auctions will start being held twice a month.

At today's auction Fonterra added adding buttermilk powder (BMP), high-heat heat stable skim milkpowder (HHHS SMP) and anhydrous milkfat (AMF) in bulk bins to the products on offer.