The prices supermarkets had to pay suppliers to stock their shelves were 10.2 per cent​ higher in November compared with a year ago, data from economists at Infometrics shows.

Many households have been struggling with rising grocery prices and the Infometrics-Foodstuffs Grocery Supplier Cost Index shows why.

In November, supermarket suppliers increased the prices of nearly 7800​ grocery lines.

The lowest annual supplier price rises were for bulk foods, tinned and processed foods, and bakery goods, but the price of food shipped in from overseas was up 22 per cent.

'Every month, the Index tracks what it costs supermarkets to buy the goods to put on the shelf,” says Infometrics principal economist Brad Olsen.

The prices suppliers charge to supermarkets make up nearly two-thirds of the supermarket on-shelf price, says Olsen.

He says 11 per cent​ of the 7800 items that suppliers charged more for, cost supermarkets more than 20 per cent more than in November the previous year.

Fresh, healthy foods saw the biggest increases, with supplier prices for fresh produce rising by just under 20 per cent​ on average.

Imported prices for cereal were up 26 per cent​.

Supplier meat prices rose by just over 12 per cent​, and both seafood and frozen food saw increases of more than 10 per cent​.

There were local and international factors driving the increases, says Olsen.

Fuel prices may have eased in recent weeks, but diesel was still 29 per cent​ more expensive in November than in the same month last year, he said.

New Zealand on-farm expenses increased 15 per cent​ between November last year, and the same month this year.

Recent weakness in the New Zealand dollar also contributed to the increased cost of importing food.

As well as high fuel prices, which can be traced back to the war in Ukraine, fertiliser costs were up 37 per cent​, and interest costs were up 34 per cent​, he says.

Tinned and processed foods had tended to have more stable prices, but, Olsen says: 'Recent acceleration in the costs of less volatile items like general grocery goods reinforces pervasive cost pressures.”

Some grocery supplier prices had fallen, with coffee and cooking oil both down.

-Rob Stock/Stuff.