Morrisons has reduced its fuel prices by 12p per litre for petrol and 8p per litre for diesel.
The supermarket described the move as "the biggest fuel price reduction in recent times".
Oil prices have plunged in the past few weeks since Covid-19 took hold across Europe.
They were also heavily dented when Saudi Arabia, which produces around 10% of the world's oil, decided to slash prices and ramp up production in a trade war with Russia.
The price of a barrel of Brent crude oil, the most used measure, has fallen by around 60% since the beginning of the year.
It slipped another 5.7% to 25.53 US dollars per barrel on Monday.
Latest Government figures show the average price for a litre of fuel at UK forecourts on March 16 was 120.3p for petrol and 124.4p for diesel.
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