Motorists are forming queues outside Gull petrol stations in Auckland as they cash-in on a temporary drop in prices at the pump.

Drivers can save up to 20 cents a litre until midday tomorrow - one motorist told Newstalk ZB their usual $160 petrol bill cost them just $100.

AA petrol price spokesperson Mark Stockdale says he isn't surprised queues are forming, and that it's sparked a price war.

Listeners are reporting other petrol stations dropping their prices to match Gull's.