Sainsbury’s has reported record Christmas sales of more than £1bn across the group.
But the supermarket giant said like-for-like sales sales only rose 0.1% in the 15 weeks to 7 January.
Argos, which Sainsbury’s bought last year, had strong sales over Christmas and Black Friday.
But Chief executive Mike Coupe said the “market remains very competitive and the impact of the devaluation of sterling remains uncertain”.
Sainsbury’s Christmas quarter sales beat expectations. Analysts had predicted a fall in like-for-like sales of 0.8%.
Food sales have been buoyant for retailers over Christmas period, according to a report by the British Retail Consortium on Tuesday.
And Morrisons reported its strongest Christmas sales for seven years on Tuesday.