Motorists face record diesel prices The price rise was the "steepest and fastest" ever seen, said the RMI, which represents almost 6,000 independently-owned filling stations across the UK. The RMI said that it is only a matter of time before petrol retailers pass the increases on to motorists. Brian Madderson, RMI Petrol chairman, said the rise had been so rapid that retailers had had "scant time to react over the holidays." However, given fuel retailers" "wafer thin" margins, he said they would have little option but to jack up prices over the coming days. "I would expect them reluctantly to push these rises through," he said. "That's more pain for the consumer and for high-street retailers, who are already squealing that people are not spending in the shops because of the high cost of fuel," said Mr Madderson. He warned that food prices could rise as a result of high diesel prices. This is because 80 per cent of the UK's food is distributed by road and supermarkets and their suppliers could look to recoup the extra distribution costs by raising prices. The price of unleaded petrol could also overtake its record high of 137.4p per litre at some point this year. Unleaded petrol cost 132.3p a litre at the end of last week. Mr Madderson said that with prices at the pumps rocketing, there was an overwhelming case for "reform of fuel taxation" in Britain, whose duty rates on diesel are the second highest in the EU. The UK's high fuel duties, which disproportionately hit the poor, were "undermining society and our economic recovery," he said. The RMI will discuss the issue with Danny Alexander, chief secretary to the Treasury, later this month.