The Co-op unveiled strong Christmas sales on Tuesday and stood by plans to spend almost £2bn ($3bn) next year on its food business in spite of the darkening economic outlook.

Sales in the food retailer’s shops were 6 per cent higher in the three weeks to January 3 than last year, after stripping out fuel and the effect of new store openings. That bumped up sales growth for the fourth quarter to 5.2 per cent.