A surprise surge in dairy prices.

The Global Dairy Price has rocketed past the $3000 mark to $US3,327 a tonne. It's a jump of 11.4 percent.

The index is now at its highest level since July 2014.

Breaking that down, Whole Milk Powder was the big winner - up 19.8% to $US3317 per tonne.

J-M-I-S Limited director Andrew Kelleher says that's an unexpected and incredible jump.

He says the market was expecting a lift of about 10 percent for that key Whole Milk Powder price.

Mr Kelleher says it means recent concerns around supply levels may have been somewhat understated.