Petrol prices have crept up overnight to reach a new high of $2.40 per litre in some areas, days out from the introduction of a new fuel tax.
Across much of the South Island and in Wellington people are paying $2.40 or more for 91 at the pump, while in Auckland prices are around $2.30 a litre, according to PriceWatch.
It comes just days out from the introduction of a new nationwide petrol excise duty of 3.5 cents per litre, which takes effect on September 30.
Further 3.5 percent increases will be introduced in 2019 and 2020. Road user charges will see the same increases on October 1, and in 2019 and 2020.
The Government says the taxes will fund $5 billion in transport investment over the next decade.
Brent crude, the benchmark measure for global oil prices, has surged to its highest level since 2014 at $US 81.20 a barrel on Monday.
A spokesperson for Z energy said: "Z reviews its pricing daily and the latest changes to the price at Z is due to high barrel price and a low Kiwi dollar. Z's fuel pricing decisions are made completely independently of all taxes, which are decided on and enforced by the government."
Analysts told the Wall Street Journal US-Iran economic sanctions are impacting prices, as is a recent decision by the Organization of the Petroleum Exporting Countries (OPEC) to hold supply constant, and declining exports from Venezuela.
President Trump hit out at the OPEC on Twitter earlier this week, demanding it increase supply and bring prices down.
"We protect the countries of the Middle East, they would not be safe for very long without us, and yet they continue to push for higher and higher oil prices! We will remember. The OPEC monopoly must get prices down now!" he said.