Morrisons has come out best in a survey by the National Farmers' Union tracking retailers' support for chilled British lamb.

As part of the union's Storewatch initiative, 50 farmers went to supermarkets in England and Wales to find out which supermarkets were stocking chilled New Zealand lamb as well as British lamb during the latter's six-month season.

Morrisons was named as the top-performing store both in terms of its range and the fact it stocked 100%-chilled British lamb. M&S, Asda and Sainsbury's were also praised for selling more British lamb than at the same time last year. Tesco had a wide range but was criticised for stocking chilled New Zealand product under the Finest label.

Some 90% of stores visited were rated between "average" and "very good" for their availability of lamb in general. About 75% of all lamb currently in stores is British, with the remainder sourced from New Zealand.

Storewatch was launched last month after farmers claimed retailers were not doing enough to support chilled British lamb in season.

Despite the good performance from a number of retailers, most could still do more to promote regional British lamb, said NFU chief livestock adviser Peter King.

This could in part be achieved by better labelling with regard to origin, he said. "There's some confusion on labelling. The Asda Smart Price labelling, for instance, is unclear," he said. "And the labelling in some ready meals in some retailers is also confusing."

King also welcomed a commitment from M&S chief executive Stuart Rose, announced last week, to stock chilled British lamb out of season provided farmers could guarantee quality, adding that if more retailers were to adopt long-term UK sourcing commitments then it would allow farmers to guarantee better quality for longer periods.

"If more retailers had planned forward then they could have sourced British lamb for a longer part of the season," he said. "I don't believe the argument that you can't get quality UK lamb after Christmas."