Salad producers said they enjoyed the run up to Christmas, with sales of salads up 10% to almost 10 million bags.

The Fresh Prepared Salads Producer Group, which supplies salad packs to major UK supermarkets, said the extra trading day and greater health awareness helped provide a year-on-year increase.

Asda said its total salad business grew by nearly 40% during Christmas week. The retailer quoted TNS data for the 12 weeks ending 31 December showing growth of almost 20% in its salads.

Asda's produce buyer for salads, Werner Neuhoff, said: "We've introduced new lines and we've also been running a series of offers that helped drive sales."

Florette reported successful special promotions and a year-on-year increase in sales of 8% in December, giving the company an 8% share of the market worth about £35m. "Added-value promotions attracted shoppers," said Florette UK's MD, Mark Newton.