Sainsbury's said that from Friday it would be cutting its petrol and diesel prices by up to 2p a litre.
Earlier, Morrisons said it was cutting the price of its petrol by up to 2p a litre and diesel by 1p a litre.
Sainsbury's head of fuel Richard Crampton said: "We're always looking at ways to help save customers money, especially in the run up to the bank holiday weekend."
Morrisons petrol director Mark Todd said: "With a sunny bank holiday weekend predicted, we're expecting to see high numbers of motorists filling their tanks for family trips out. That's why we're passing on these savings in time for the pre-bank holiday shop."
These are the latest in a series of reductions by supermarkets over the last few weeks.
Morrisons has 314 petrol stations across the UK and Sainsbury's 281.
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