After a lukewarm reception to his Budget this week, the Chancellor George Osbourne has come under fire for refusing to drop the 3p rise on fuel duty in August as pump prices hit a new record high. Over the last three weeks, analysts have recorded a rise of 2.75p for the price of unleaded petrol.

The average unleaded price recorded at the pumps has now reached more than 140p per litre for the first time ever following a slow upwards trend over the last few weeks. For diesel, the price is now well over 146p per litre, on average. Analysts from the AA say that the average car owner will now spend well over £8 per month more on fuel than they did last year. Once the 3p duty increase takes effect, this will rise to a £12 per month increase since January 2012.

The rise in the cost of fuel is thought to be due to a rise in wholesale prices, coupled with concern about the political situation in Iran. In total, crude oil prices have risen by 12% in the last four months and it is now trading at around £78 per barrel. The technical director of the RAC, David Bizley, called the rise a “painful barrier”, adding that further cost increases were likely to follow. The Bank of England agreed, adding that any further problems in the Middle East are likely to have “significant implications” for oil prices. It also cited a growing demand for oil as a significant factor.

Any further rises in the cost of fuel will provide more ammunition for those who want to see the forthcoming 3p duty increase scrapped. Among them is Labour’s Treasury spokesperson Cathy Jamieson who said George Osbourne was “out of touch” with middle income families.

However, the Business Secretary, Vince Cable, backed the Chancellor’s decision, saying the government were caught in a “dilemma”: “We could stop all of it but it’s extremely expensive… we’ve got to strike a reasonable balance.”