Fuel prices rose six cents per litre during September following a commodity price rise earlier in the month.

But the AA says retail prices should now be falling again after a slight improvement in the New Zealand exchange rate.

Photo: File.

'In the AA's view, when fuel companies raised prices by six cents per litre in the first half of September, they increased their margin above the norm,” says AA PetrolWatch spokesperson Mark Stockdale.

'The fuel companies should now be dropping retail prices by two-three cents per litre.” While commodity prices had increased by 10 per cent, which sounded like a lot, the AA says motorists should not expect retail prices to rise by the same amount.

'Because commodity prices only make up about a third of the retail price of petrol, pump prices should only change by about a third of that amount,” says Mark.

According to AA PetrolWatch, the price of 91 octane petrol at most outlets ended the month on $2.04 per litre, with diesel prices in many of the main centres rising to $1.26 per litre.

However, in some locations prices were 14 cents per litre or more below that due to local competition.