The cost of petrol has dropped below £1 a litre at Asda and Morrisons after the supermarket giants responded to the falling price of oil with a new round of cuts.

Asda slashed the price of unleaded at its 170 forecourts by 5p to a new mark of 99.9p – meaning the supermarket has cut the price of a litre by around 15% in the last three months. Diesel drops to 110.9p a litre.

Morrisons followed the move to 99.9p with reductions of up to 7p per litre, while Tesco and Sainsbury’s – which both price their petrol locally rather than on a national basis – are expected to announce price cuts of their own in due course.

The cuts come with the price of oil having almost halved from record highs earlier this year amid the economic upheaval.

“We are committed to delivering the best value to customers across the board and we review our prices daily to achieve this,” said ASDA trading director Darren Blackhurst.

“Drivers should not be paying more than 99.9p a litre for unleaded fuel based on current oil prices. Past experience tells us that unless they live near an ASDA they still will be.”