The government has been urged to take quick action to help the 1.7 million homes that still use heating oil and have seen prices double due to the US attacks on Iran.

These are often people in rural areas, who have seen prices for their fuel jump in some cases from 62p a litre before the war to perhaps £1.73 now.

Suppliers have been accused of delivering supplies without a price being quoted, leaving consumers in for a nasty shock when the bill arrives.

Conservative net zero minister Clare Coutinho wants the Competition and Markets Authority (CMA) to probe the suppliers and order them to be fairer to consumers.

Speaking on the BBC Today programme this morning, Ms Coutinho said: “Heating oil is being delivered without a price being quoted. We have called on the CMA to investigate these practices. We want more transparency and fair practices for consumers.”

Chancellor Rachel Reeves says she has asked the CMA to be “vigilant”, but Ms Coutinho accused the government of being “slow off the mark”.

“I hope this is something we can work on together. It is people who are vulnerable and in rural communities who have no other choice,” she added.

All energy costs are rising as fears grow of a supply squeeze. But heating oil seems to be the energy supply that is being most badly hit. There are about 120 heating oil suppliers, much smaller firms than the large energy conglomerates that supply electricity and gas to most of the population.

Emma Simpson, chief executive of Rural Action Derbyshire, a charity that runs an oil-buying scheme, said: “People who rely on heating oil are facing a sudden and frightening surge in cost. We may be heading into spring, but anyone running low on oil right now doesn’t have the luxury of waiting for prices to fall.”

She added: “For some, the decision to order or not will come down to whether they can realistically afford it, and that is a really hard position to be in.”

There were wild swings in both the oil and equity markets on Monday. But on Tuesday, oil prices fell sharply and stock markets bounced back as US president Donald Trump said the US-Israel war with Iran could be over soon.

The price of Brent crude was more than 8 per cent lower at just under $91 dollars a barrel, retreating from near-four year highs above $100 a barrel in volatile trading on Monday.

Markets responded by recovering some of the recent ground lost in the sell-off, with the FTSE 100 Index up 1.6% soon after opening, up 165.3 at 10,414.8.

Lindsay James, investment strategist at Quilter, said: “Markets are attempting to stabilise after an extraordinary round trip in oil prices that saw prices collapse from an intraday high of nearly $120 a barrel back towards the low $90s, helped in part by President Trump signalling that the war with Iran could be ‘very complete, pretty much’.

“Equities in the US responded in turn with modest gains while Treasury yields reversed, ending the day fractionally lower.”

Matt Britzman, senior equity analyst at Hargreaves Lansdown, said: “Global equity markets are still taking their cues from oil this morning – but the tone has notably improved after yesterday’s wild swings.

“What initially looked like a one-way surge in energy costs and the inflation headaches that come with it has started to stabilise, offering some much-needed breathing room.”