A slump in toy and gaming sales saw Sainsbury's record a 0.7 per cent decline in sales over the Christmas period.

In a third-quarter trading update released this morning, the supermarket giant said that grocery sales had increased during the period, but poor merchandise sales had led to an overall decline.

The update revealed that Sainsbury's saw 32 million customers shop in one of their stores in the key Christmas week.

Online grocery sales were at record numbers throughout the Christmas period, while Argos - which was taken over by Sainsbury's in 2018, recorded its best ever Black Friday.

Chief executive of J Sainsbury PLC Mike Coupe said: "We gave our customers a great combination of quality food at good prices this Christmas and we delivered a standout performance operationally.

"We have a real sense of momentum in Sainsbury's and investment in our stores and improvements to service and availability have led to our highest customer satisfaction scores of the year.

"Our digital investments are also paying off and over 20per cent of our business was online in the quarter.

"Groceries Online had record order numbers throughout the Christmas period and customers are increasingly choosing to shop with SmartShop in our supermarkets.

"Argos had its biggest digital Black Friday to date and record sales through mobile and via Argos Click and Collect.

"32 million customers shopped with us across Sainsbury's and Argos in the key Christmas week.

"The colder weather helped to deliver strong clothing sales in the quarter and our Christmas, party and gifting ranges were all popular with customers.

"Argos outperformed the market in consumer electronics, but the toy and gaming markets declined year on year.

"Thank you to all of our colleagues for working so hard over this key quarter and for delivering great service and availability for our customers in stores and online."