Asda, the Walmart-owned supermarket chain, said second-quarter sales rose by 3.8% as online sales doubled.

The grocer added it intends to increase the number of delivery slots it has available to one million by 2021 having already raised the total by 65% to 700,000 since March.

Asda also plans to extend to its trial with Uber Eats to 25 more stores over the next eight weeks, while its express click and collect service is being reinstated at more than 300 stores.

Roger Burnley, Asda’s chief executive and said: “The pandemic has created a structural shift in customer behaviours towards grocery shopping.

“We have accelerated our online capacity expansion to meet levels we had anticipated reaching in eight years within a matter of weeks and we will continue to expand this offer.”

Burnley said demand for clothing declined, except for children, especially where there was an uplift in sales of pyjamas, jogging bottoms, multi-pack shorts and t-shirts.

August has also seen fuel volumes return to around 90% of pre-COVID levels, said Asda, though customer spend at the pump remains down year on year.

Sales of camping equipment are also up 25% year-on-year, it said.