Petrol prices are on the rise again, hitting their highest level for more than two years.

Overnight the price of a litre of 91 octane petrol rose 3c to $2.02 and 95 octane rose to $2.11.

Last month when the price of 91 octane petrol hit $2 a litre, AA PetrolWatch said it was the highest it had been since August, 2008.

At $2 a litre, the average car would cost between $120 and $140 to fill - an increase of $20 on a year ago, said AA. The latest increase is likely to add between $1.20 and $1.40 to the bill.

The rise by Shell, BP and Caltex followed a rise in the international price of crude oil and a fall in New Zealand's exchange rate against the US dollar.