According to the latest figures released by ARVAL PHH, prices across 12,000 petrol stations have risen from an average of 70.53ppl on March 1 to 75.42ppl on the week ending April 26.
Diesel rose from 74.72 ppl to 77.04ppl over the same period. A similar hike to petrol was offset by the time of year - as heating gets switched off the demand for heating oil drops, meaning diesel can be produced more plentifully, which keeps prices down.
Danny Clenaghan, managing director of fuel and business solutions at ARVAL PHH said: 'Although the Budget froze fuel duties, other factors may push up pump prices. 'For example, uncertainty in the Middle East has already contributed to the latest price rises and further volatility in the crude oil market may sustain this trend.
'The Budget was a golden opportunity for the Chancellor to reduce fuel taxes to bring us into line with our European neighbours. However, our fuel duties, and prices, remain the highest in the EU.
'British businesses continue to suffer competitively because of their excessive fuel costs.'
There is some good news on fuel for fleets. Asda has launched a petrol price war, cutting 1.2p a litre off the price of unleaded at 142 of its filling stations, to an average of 73.6ppl. Morrisons has responded with a one pence cut of its own at its 90 sites, and Tesco has promised to match the price of any garage within a three mile radius.