Half of voters are tightening their belts in response to the Iran war by spending less, filling up their cars and cutting energy use amid fears the conflict will deepen the cost of living crisis.

Despite Donald Trump’s war in the Middle East only being a month old, half of voters (50 per cent) said they were changing their behaviour to respond to the conflict compared to 37 per cent who are not, according to a BMG Research poll for The i Paper.

The findings could set alarm bells ringing in the Treasury amid worsening economic forecasts as they point to reduced spending and confidence, and came even as Chancellor Rachel Reeves promised to cushion the blow of the war on household finances.

BMG pollster Catherine Lethbridge said there were “clear signs that fears over energy supply and rising costs are already shaping everyday decisions” of voters.

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Voters are responding to soaring oil and gas prices and tanking stock markets by spending less on non-essential items such as eating out (21 per cent of those surveyed), buying fuel earlier than usual (20 per cent), being more cautious about big purchases (19 per cent) and changing energy use (17 per cent). Some are changing travel plans, including holidays and flights (12 per cent).

It came as the RAC found that the cost of filling a typical family car with unleaded petrol is almost £7 higher than at the beginning of March, at nearly £80. The average price for a litre of petrol has risen above 150p for the first time in nearly two years, with diesel standing at more than 177p, with the boss of Asda warning of bumper demand at some pumps due to rising costs.

As attention also turns to a looming spike in household energy bills, British voters largely backed the approach set out by Reeves to target support at low-income households (53 per cent) rather than offering universal support (30 per cent) of the type offered under Liz Truss after Russia’s invasion of Ukraine.

Labour, Reform and Conservative voters were all also broadly supportive of sending Royal Navy ships to the Strait of Hormuz to protect shipping and get oil and gas moving out of the Gulf again, with 41 per cent backing such a move compared to 23 per cent opposed.

It suggests Sir Keir Starmer’s response to the war has public support as he coordinates a plan to reopen the Strait, after polling last month suggested voters backed his decision not to join the US in bombing Iran.

However, there is growing pressure on the Prime Minister and Energy Secretary Ed Miliband to lift the ban on new oil and gas drilling in the North Sea, with nearly half of voters (48 per cent) saying the UK should allow more exploration to boost domestic energy production even if it makes it harder to reach net zero targets.

Only a quarter (26 per cent) backed Miliband’s approach by saying drilling should be kept at current rates to help meet net zero targets, even if it means relying more on imported energy.

Despite this, there is no consensus on whether this would actually cut energy bills, with only around a third (32 per cent) thinking it would lead to lower costs, while there was backing for both increasing oil and gas drilling (47 per cent versus 17 per cent opposed) as well as more investment.

Although the conflict has directly led to worsening economic forecasts, voters hold Labour more responsible for the cost of living crisis (29 per cent) they are currently experiencing than Trump (22 per cent) and the last Conservative government (11 per cent).

BMG pollster Lethbridge also pointed out that while the current Government is blamed more than anything else for the cost of living crisis there are splits along party lines.

“Party loyalties shape the blame game,” she added.

“Labour and Conservative voters tend to accuse each other, while Trump’s role is acknowledged at similar levels across both groups.

“Reform voters, however, stand apart, overwhelmingly blaming the current Government and largely dismissing US influence altogether.”

BMG surveyed a representative sample of 1,507 GB adults between 25 and 26 March. BMG are members of the British Polling Council and abide by its rules.