Sainsbury is expected to update the City with first-quarter trading figures on Wednesday (21 June).

Analysts are predicting that the supermarket group will reveal like-for-like sales for the 12 weeks to 17 June of around 5.5%.

They also expect the retailer to have benefited from the World Cup and the recent hot weather as customers stock up on alcohol, snacks and barbeque food.

Last month Sainsbury recorded a full-year pre-tax profit to end March 25 of £104m, up from a loss of £238m the year before.

Total sales increased 5.7% to £16.987bn, while like-for-like sales growth, excluding petrol, was 3.7%.

However, analysts remained cautious. Darren Shirley, from Shore Capital, said: “It will get tougher in the final quarter. Sainsbury CEO Justin King had some quick wins initially but the biggest challenge is turning sales growth into profits growth. He's been on a bit of a profits holiday.”

Sanjay Vidyarthi, from Teather & Greenwood, added: “We're still waiting for an earnings upgrade, but I'm not sure how easy it will be to do when you've got Asda particularly attacking on price.”