Morrisons and Asda have cut the price of petrol for the second time in a week amid a supermarket price war prompted by sharp falls in the underlying price of crude.

Early on Friday Morrisons leapfrogged Asda to offer the cheapest petrol price among the major supermarket operators, capping unleaded at 112.9p and diesel at 113.9p.

Hours later Asda responded with a cut to 112.7p for both unleaded and diesel.

The cuts this week will save more than £1 on a typical fill-up.

Rivals Tesco and Sainsbury’s are now expected to chop their forecourt prices in the wake of the oil price plummeting to a five-month low on world markets. Soaring US fracking production, weak demand in China and jitters about Opec organising any further supply cuts have all contributed to a global glut of crude.

Brent crude is currently trading at $48.64 (£37.59) a barrel, compared to $56 in early April, a drop of 13%.

Cheaper petrol prices will bring welcome relief to household budgets hit hard by rising inflation in recent months. The average petrol price jumped from a low of 101p in February 2016 to 120p in March 2017, and has been a central factor in pushing up the consumer price index.

RAC fuel spokesman Simon Williams said: “It’s great to see the supermarkets responding to our call to pass on wholesale fuel price savings to motorists at the pumps. This will help to reduce the cost of driving for millions by taking the average price of petrol down from 118p a litre to around 116p – a price last seen in December.”

Roger Fogg of Morrisons said “Morrisions was the first to cut prices on Wednesday and is again leading the price down following a 5% fall in the oil price on Thursday. We are responding quickly for our customers as many will be filling up at the weekend.”