The Office of Fair Trading said its investigation into the UK fuel market identified a lack of pricing information on motorways as a concern and it not rule out taking action in some local markets if there was "persuasive evidence of anti-competitive behaviour".
In August 2012, prices were on average 7.5ppl higher for petrol and 8.3ppl higher for diesel than at other UK forecourts.
Despite enormous price rises in the last few years, an Office of Fair Trading report into the UK's fuel market found it is 'working well'.
Pump prices are rising yet again. The wholesale cost has risen almost seven per cent since Christmas alone. Now they want answers.