The UK's three biggest supermarkets have pledged to increase the amount of British pork they sell in response to damning new figures showing their support to be waning.

Analysis by the National Pig Association's PorkWatch survey of the 12 leading supermarkets' pork sourcing policies over the past year shows the level of British pork on shelves has fallen from 78% in March to 74% last month.

The worst offenders were Tesco, where British pork fell from 70% in March to 60% in September, and Asda, which dropped from 75% to 67%. Budgens was 100% British in March but only 87% last month, while Sainsbury's dropped three percentage points to 77%.

Aldi, which now stocks 100% British, Netto and Somerfield increased their levels of British pork, while The Co-operative Group, Morrisons, Waitrose and M&S already stocked 100%.

NPA chairman Stewart Houston wrote to all the supermarkets last week to demand they support the British industry or risk sending it back into crisis. Since receiving the letter, Tesco, Sainsbury's and Asda have all moved swiftly to reassert their commitment. Tesco wrote to Houston to commit to returning to previous sourcing levels or beyond, as well as pledging to feature British pork more prominently in upcoming price and volume promotions.

Asda has said it will look to increase the percentage of British pork it sells over the coming weeks, although it warned seasonality would play a part in how much it could source. The NPA has arranged a meeting with the supermarket for early November to discuss the situation further.

Sainsbury's reaffirmed its commitment to moving progressively towards making its pork 100% British.

Houston welcomed the retailers' response as a positive step, but warned that it by no means solved the lack of collaboration. "This addresses the short-term problem, but the long-term issues still remain," he said. "The supply chain is still broken and there is a disconnect between the parties concerned."