Petrol prices have fallen to a two month low, dropping around 18c a litre in that time.

The drop is being credited to falling oil prices and a rising exchange rate.

The New Zealand Automobile Association says prices have fallen a total of 6c per litre in the just last few days.

The current national average price for 91 octane is sitting at nearly $1.83 a litre, while 95 octane is $1.91.