Kiwis are being warned petrol prices could rise above $3.50 a litre when the Government's 25 cent reduction in fuel excise tax ends.
The tax reduction, which came into force in April, is set to end in July - unless extended.
And despite the tax cut, prices are already climbing again with 91 hitting $3 a litre in parts of the country.
Waitomo group managing director Jimmy Ormsby told AM's Melissa Chan-Green prices will only get worse when the tax relief ends.
"Unfortunately there's no limit, there's no cap," Ormsby said when asked how high prices could rise. "Anything over $3.50 a litre wouldn't be a surprise to me but hopefully it doesn't get to that, hopefully there is some relief."
Ormsby said the price increases aren't being driven by companies trying to make huge profits.
He said international pressure from the Ukraine invasion and high inflation is hitting petrol companies hard.
"The price increases have been quite relentless but they're based on the price of crude which is a supply and demand imbalance at the moment.
"We are all pretty aware of what's happening in Ukraine and on the supply side, there's a lack of supply coming out of Russia because of boycotting.
"We've all got our own business costs and those are all under pressure at the moment as well with inflation and cost of living and cost of wages going up. We are not immune to that," he added.
Ormsby said the Government should continue the tax reduction beyond the initial three months to help give motorists some relief.
"Any relief for the motorists. It's the people that can least afford it that are hurt the hardest by high fuel prices."
He also called for the Government to remove Auckland's regional fuel tax.
The Government announced plans to slash the fuel excise tax in March after coming under heavy scrutiny for high prices amid the cost of living crisis.
Along with the tax cut, the Government also halved the cost of public transport in an effort to help struggling Kiwis.
The US crude oil price settled below $100 a barrel on Tuesday to its lowest level in two weeks.
US West Texas Intermediate crude settled down $3.33, or 3.2 percent, to $100.11 a barrel, while Brent crude was down $3.48, or 3.28 percent, at $102.46 a barrel, according to Reuters.
