More than 30 MPs are backing a campaign for the competition watchdog to fully investigate fuel prices amid national media stories concerning the apparent ‘rip-off’ cost of diesel.

Fuel price campaigner FairFuelUK has revealed via Twitter and on its Facebook page that 32 MPs from across all parties have pledged their support this week to its campaign for the Competition and Markets Authority (CMA) to look at retail price changes in relation to oil cost fluctuations, commodity speculation, wholesale prices and distribution costs "to stop further blatant, opportunistic and unfair profiteering taking place at the pumps".

Earlier this week the same group had written an open letter warning Chancellor George Osborne that an inflation-based fuel duty rise in the coming Emergency Budget or in future years would “lower GDP, cost the UK £8 billion in reduced economic activity, raise inflation and sabotage one of the slowest economic recoveries this country has ever seen”.

The letter said the UK already has the highest duty regimes in the EU; 98% of FairFuelUK’s 1.1 million supporters believe this is too high; and research by CEBR confirm that fuel duty is already at an unsustainable level.

“To ignore 37 million drivers, deny the fact we are reliant on a road economy and side-step haversacks of prestigious academic fiscal research will seem arrogant and reckless.”