The RAC predicts we are about to see the end of petrol being sold for less than £1 a litre.
The warning from the automotive services company follows Tesco raising its prices above the £1 mark. It is the first supermarket to do so, taking the average cost of unleaded petrol to just under 103p a litre.
At some of its filling stations, the supermarket is now charging 100.9p per litre for unleaded petrol. Reports say that Morrisons has also put its prices up.
While they have not yet followed suit, Sainsbury's and Asda are reviewing their pricing.
Tesco said a 3p per litre rise in wholesale prices was the reason behind its petrol price rise.
By Easter, the RAC predicts motorists will be paying an average of 3p per litre more for their petrol. If this happens, the cost of filling up the average family hatchback will increase by around £1.60.
RAC fuel spokesman Simon Williams said: "With two supermarkets now having increased their prices at the pump, we may well see others follow suit this week unless they're prepared to absorb increased wholesale costs for the benefit of their customers.
"As a result we're seeing average prices rise slightly, with a litre of unleaded petrol now being sold for a little under 103p and diesel for just over that price."
However, a sudden price increase is unlikely as the Chancellor has announced fuel duty will be frozen for the sixth year in a row.
Are you surprised by the rise in petrol prices?