The organsiation says that from Monday 19 December to Thursday 5 January the cost of diesel increased by nearly 4.50ppl and unleaded petrol by as much as 5.00ppl without factoring in the 20% VAT rate.

Such increases have been so rapid that retailers haven't reacted yet but RMI Petrol warned that prices will be moved upwards quickly from now by retailers desperate to protect their 'already wafer thin margins'.

The rises were attributed to growing tension between Iran and the West over their nuclear intentions, which has led Iran to threaten to blockade the Straits of Hormuz through which 30 to 40% of the world’s oil supply is shipped.

In addition, RMI Petrol pointed to the decision by Repsol, Spain’s largest oil company, to halt production  at its Petronor refinery near Bilbao because of weakening profit margins, and cash flow strains from high pricing, which have forced companies to balance their end of year positions and cut stocks to very low levels.

Brian Madderson, chairman of RMI Petrol, commented: 'This is a very worrying development but not entirely unexpected. I wrote to the Chancellor on 2 January highlighting the serious supply issues ahead and enclosing a report "The case for reform of fuel taxation" as it is the Government’s only direct control over rocketing fuel prices which are undermining society and our economic recovery.'