Petrol prices rose by 5c a litre on Friday, for the second time in three days.
Unleaded 91 fuel at Shell, BP, Mobil and Caltex now costs $1.429 a litre and 96 octane is now $1.479.
Mobil's spokesperson Alan Bailey says the cost or refined oil in Singapore, and the continual weakening of the New Zealand dollar are the main reasons for the rise.
The price of diesel remains unchanged.
Gull says it will keep the price of 91 at $1.369 a litre and will review it again on Saturday.