Grocery costs remained largely unchanged over the Christmas period

The latest Infometrics-Foodstuffs' Grocery Supplier Cost Index shows grocery costs have increased 2.4 percent in the year to December, driven by rising seafood and meat prices.

Infometrics Principal Economist Brad Olsen says overall - costs haven't increased much in December.

He says the only items that tend to change over the period are seasonal and perishable.

Olsen says the costs of potatoes and kiwifruit increased, due to sustained demand and potentially less supply at this time of year.