A weaker New Zealand dollar has meant that petrol prices around the country have increased by 6 cents a litre in less than a week.
The major fuel companies raised the main port price of fuel by 3 cents a litre on Thursday night.
Now a further price increase has pushed petrol prices to the highest level in more than two years.
According to data collected by the Automobile Association (AA), petrol prices are now at their highest since July 2015.
The increase comes after the New Zealand dollar fell suddenly in the weeks post election, while oil product prices have also been steadily rising.
AA spokesman, Mark Stockdale, said while the first of the increases could be justified by a weaker New Zealand dollar and stronger commodity prices, there was no further move, which would warrant a second jump.
“The AA can’t see any justification for why prices have gone up another 3 cents. There’s been no further deterioration in the exchange rate or rising commodity prices to explain it,” Stockdale said.
“When fuel prices don’t move in relation to observed changes in commodity prices and the exchange rate, motorists deserve an explanation.”
The New Zealand dollar is stronger against the US dollar than it was at the start of the week, which would tend to lean in the favour of making petrol cheaper.
A spokeswoman for BP said the latest increase was “predominantly driven by an increase in the cost of product, and further movement in the exchange rate”.