The RAC data is based on the average price of diesel at a range of supermarkets, motorway service stations and independent retailers.
Simon Williams, RAC’s head of policy, said the diesel record “spells pain not only at the pumps for drivers, but for everyone who buys goods or services that rely on diesel lorries and vans”.
“Undoubtedly these increased costs will be passed on to consumers,” he said. Williams said prices at the pumps will not come down until there is a “sustained lower oil price – over several weeks, not days”.
The price of Brent crude, a benchmark for global oil used to make petrol, diesel and other fuel products, rose over the weekend and is now hovering at around $108 per barrel. Before the US invaded Iran, it was trading at around $73.
Supplies of diesel internationally have been heavily constrained by the conflict in the Middle East, which has restricted the flow of both crude oil and refined diesel onto global markets.
Russia, which is also a major producer, has also implemented an export ban on diesel, following attacks on its refineries by Ukraine, further limiting supply.
Diesel is harder to refine than gasoline and, because it is used by the haulage industry and in agriculture, it is very difficult to reduce demand.
The UK is heavily reliant on imports. Although the four refineries in the UK make more than enough petrol to meet demand, they do not make enough diesel for the country’s needs.
There were 15.1 million diesel vehicles on UK roads at the end of June, according to the Department for Transport. That is a drop from 15.7 million a year before.
There were 9.8 million diesel cars, down year on year from 10.4 million.