Rachel Reeves has refused to rule out ditching a planned fuel duty increase in September, as she promised “nothing is off the table” to help consumers with rising energy costs amid the Iran conflict.

The chancellor told MPs on the Treasury select committee that options for “targeted support as well as broader measures” were being explored, although she cautioned that it remained “too early” to be sure emergency help was required.

Against a backdrop of volatile conditions in energy markets amid the US-Israel war with Iran, Reeves said the government was prioritising the de-escalation of the conflict and pushing for the safe passage of oil and gas exports through the critical strait of Hormuz.

She said Britain was also “willing to play its part” to release strategic oil reserves alongside other countries in the 32-member International Energy Agency, in a push to bring down crude prices that have soared.

However, she signalled the Treasury was working on contingency plans for an emergency energy support package to help British households bracing for a sharp rise in living costs.

“Nothing is off the table at this stage. We are looking at targeted support as well as broader measures but it is just too early to say what is needed.”

Asked by Conservative MPs whether she would rule out addressing a planned increase in fuel duty from September – when a 5p cut made after Russia’s invasion of Ukraine in 2022 is scheduled to be phased out – she said all options were being kept open.

“We always keep all taxes under review. But it is much too early when those changes are not due to come into effect until September to guess where petrol prices will be then,” she said.

Separately, Keir Starmer told the Commons on Wednesday: “Fuel duty is frozen. It’s going to remain frozen until September, and we will keep the situation under review in light of what’s happening in Iran.”

Reeves and Starmer have come under mounting pressure from opposition MPs, as the Tories, Reform UK and the Liberal Democrats push for the chancellor to drop the planned rise in the rate of tax on petrol and diesel.

Fuel prices have risen sharply at filling stations amid concerns the conflict in the Middle East could cause disruption to supplies while driving wholesale prices close to record levels.

Global energy prices have fluctuated wildly in recent days, with the price of a barrel of oil briefly jumping as high as $119.50 on Monday, which took it to levels not seen since 2022.

Reeves said the government would focus on preventing fuel retailers from profiteering from the situation, before a meeting with industry leaders and the Competition and Markets Authority on Thursday.

“I am very loth to spend government money on something the market should be doing itself. And that is why greater competition and greater transparency about pricing is so important,” she said.

“I would rather we had a properly functioning market where customers have decent information about prices at different petrol forecourts rather than subsidising the money which often goes to the retailer.”

Her comments come after the Office for Budget Responsibility warned that UK inflation could end the year higher than previously expected, at 3%, because of the US-Israel war in Iran.

Headline inflation in the UK is running at 3%, down from a peak of 3.8% last year, and had been expected to drop close to 2% this year.

The Treasury watchdog also warned that the chancellor could face limited room within her self-imposed fiscal rules to provide an emergency package of financial support for rising energy bills. The previous government stepped in to tackle high energy bills in 2022.

However, Reeves insisted there was “scope for interventions in the short term”, after measures to tackle elevated levels of borrowing and debt. She said the UK was also in a stronger position to respond because investment in green energy had helped to reduce Britain’s exposure to volatile global oil and gas prices.

“Over the next few years we will be even more insulated as more of that renewable energy comes online and as we build the infrastructure to better connect it to the grid.”