The Office of Fair Trading (OFT) is due to release a review into whether reductions in the price of crude oil are being passed on to motorists.
The OFT will then decide whether to launch a full investigation into fuel prices.
Edmund King, president of the AA said it was time the OFT investigated the fuel industry:
"The Office of Fair Trading decides soon whether to launch an investigation into fuel prices, hopefully tackling the fuel industry's treatment of drivers, consumers and businesses."
Brian Madderson, from the Petrol Retailers Association (PRA), called on the OFT to launch an investigation into the wholesale market rather than target petrol stations.