Waitrose is set to only sell British lamb as it phases out meat from New Zealand in order to "support UK agriculture."
The retailer used to supplement its lamb range with New Zealand products in the winter months, but is to stop doing so by 2021.
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Most of the supermarket's meat and dairy offering is already UK-grown; all of the own-brand fresh chicken, pork, beef, eggs and liquid milk is already sourced exclusively from the UK.
The company has said it wishes to "invest in the future of British agriculture" and is aiming to do more work supporting local producers.
Tor Harris, the Head of CSR, Health and Agriculture, said: "Waitrose & Partners has a long history of supporting and sourcing from local producers.
"The decision to commit to 100 per cent British lamb all year is a continuation of that commitment and means that we can extend opportunity to our existing British lamb farmers while also potentially bringing new local producers into our supply chain as we continue to invest in British agriculture."
This move has been welcomed by the National Farmers' Union (NFU) who say it "will provide a welcome boost for the UK sheep sector at a time when our future trading relationship is uncertain."
NFU livestock board chairman Richard Findlay explained: "It means the public have more opportunity to buy British, locally produced lamb reared to some of the highest and environmentally sustainable standards in the world. We know from a recent IGD/AHDB survey that almost 70 per cent of shoppers want to see more British food on supermarket shelves.
"Waitrose has previously been a strong supporter of the British livestock industry and this commitment, which will see additional British lamb producers join its supply chain, will help to ensure our sector has a sustainable and ambitious future."
New Zealand Meat Industry Association chief executive Tim Ritchie said Waitrose's move to only sell British meat would not have a significant impact on the industry.
"Over the last decade or so, [New Zealand] has diversified significantly away from some of those more traditional markets and the whole Asia region has been very positive about sheep meat, in markets like China, which is now half of our business.
"We have over 100 markets around the world that we are servicing and it is not as if we are desperately looking to find homes from product - they are there. The UK continues to be an important market, especially for our chilled lamb legs."
Waitrose had been an important customer for New Zealand since the 1980s, he said.
"From time to time companies like Waitrose they'll make strategic decisions to do things differently, and they have made the decision to phase out New Zealand lamb."
A number of supermarkets in the United Kingdom and wider Europe would continue to sell New Zealand lamb during their market's off season, he said.
- Telegraph Media Group