Petrol prices have risen to their highest level in more than two years, figures show.
A litre of petrol reached an average of £1.18 in the UK on Monday, according to data released by the Government - the highest since December 2014.
Diesel car drivers are also feeling the strain, with an average price per litre of £1.21, last seen in June 2015.
The figures from the Department for Business, Energy and Industrial Strategy show that petrol and diesel prices have risen by more than 4p per litre in five weeks.
Howard Cox, founder of the FairFuelUK campaign, warned that many motorists are being forced to pay even higher prices.
He told the Press Association: "The reported average figures hide the reality that hard-working Brits are paying even more in rural areas and where supermarkets are few and far between.
"In these areas drivers are paying as much as 12p per litre more, having no choice but to pay these opportunistic, profiteering fuel suppliers.
"With dozens of FairFuelUK-supporting MPs, we're recommending an independent PumpWatch body to ensure everybody understands how road fuels are priced for millions of drivers to get the fairest and most transparent pump deals possible."
The increase in prices follows a 24% rise in the cost of oil, from 45 US dollars (£37) in mid-November to 56 US dollars (£46) by the end of December.
This was driven by a deal between Opec and other major oil producers in November to curb output.