In a sign that authorities are worried about near record high fuel prices, the Office of Fair Trading (OFT) is calling for responses on whether prices paid at the pump are a fair reflection of underlying costs.
The OFT is also asking whether concerns about price co-ordination and the structure of road fuels markets identified by other national competition authorities are relevant to Britain.
"We have therefore decided to take a broad based look at this sector, to provide an opportunity for people to share their concerns and evidence with us," said Claire Hart, director in the OFT's Services, Infrastructure and Public Markets Group.
"This will help us determine whether claims about competition problems are well-founded and whether any further action is warranted."
In a sign of the price pressures facing petrol stations, refining margins for gasoline hit their highest in four years, while Brent crude oil prices are near all-time highs in pound and euro terms.
The OFT will gather information for six weeks and publish findings next January, it said.