Opposition parties across the political spectrum have given the government a 'fail' grade over its temporary fuel tax cuts.

Fuel taxes have been slashed by 25 cents a litre for the next three months as the government acts to counter soaring petrol prices.

National Party leader Christopher Luxon says the petrol tax tweaks will provide some relief but does not address the wider cost of living crisis.

"It's not just fuel that's gone up and petrol prices that are going up; food's up 13 per cent and weekly rents are up $150 a week. People deserve a break.

"The best way we think to do that is adjusting the tax thresholds; returning the extra tax Labour's grabbing from inflation back to people so they've got cash in their pockets."

Luxon estimates this could save the average earner $870 a week, while the ACT Party says it could deliver $187 per person through its 'carbon tax refund' policy.

ACT leader David Seymour says the refund will be taken up through the Emissions Trading Scheme and come out of what he calls the government's "climate slush fund".

"We could have given $750 [each year] back to an average family of four. In order to make those sorts of savings under Labour's scheme you'd have to buy 3000 litres a year."

The Green Party supported the halving of all public transport fares from April 1 but had also made clear it could not get on board with fuel excise cuts.

Co-leader James Shaw says direct payment supports - through the welfare system or via tax credits - is a better, greener way to go.

Green Party co-leader James Shaw says direct payment supports would have been better than fuel excise cuts. Photo: RNZ / Angus Dreaver.

"If we'd been able to provide some support either through the income support system or the tax system then people would have the choice about how to spend that money.

"If you only do it through fuel taxes then it's confined to that domain."

Shaw says the Green Party is also concerned there is no guarantee petrol companies will not just absorb the fuel tax cuts into their profits.

Minister of Energy and Resources Megan Woods has asked fuel businesses to share their rolling seven-day average fuel margins to monitor industry profits.

This disclosure is based on goodwill but Woods says she has spoken to several fuel companies and they are supportive of passing every cent on to customers.

"They all seemed very amenable to these changes. They can see on the forecourts of their petrol stations the impact this is having on Kiwis when they fill up their cars."

As the conflict at Ukraine's border and the Covid-19 pandemic wear on, it is unclear if fuel prices will be worse, better or the same in three months' time.

The government will review the fuel excise cuts before they end and has promised any drawbacks will be phased and only when fuel prices stabilise.

-RNZ/Anneke Smith.