Pig producers have urged Tesco and Asda to up the quantity of British pork on their shelves after a survey found a large proportion was imported.
According to a recent shelf-watch survey by NFU Scotland, less than half of the fresh pork on sale in the two retailers was British.
The union said the statistic was 'shocking' for the pork sector, as both supermarket chains had a 'strong commitment to source other meats from the UK'.
It comes as the UK pork sector continues to face disruption due to the Covid-19 pandemic, while exports have been made more challenging because of Brexit.
Prices have fallen below the cost of production, exacerbated by cheaper supplies being sourced from Europe.
NFU Scotland said both farmers and consumers deserved reassurances that British and Scottish pork would be readily available on every shop shelf.
Industry intelligence by the union suggests that there is a significant disparity between supermarkets on their commitment to home-produced pork.
While some supermarkets are 100% committed to British pork, Tesco and Asda are 'falling well short' of what farmers and consumers would expect.
NFU Scotland President Andrew McCornick said some retailers needed to step up to the plate during these challenging times for the sector.
“In the case of the Co-op, all fresh pork, as well as bacon and sausages are sourced from the UK, while Morrisons, Sainsbury’s, M&S, Lidl and Aldi are also coming across as very strong supporters of domestic production.
“In stark contrast, the display of pork in the Tesco and Asda stores that were examined was poor. Less than half of the fresh pork on sale was British or Scottish and that is a shocking statistic.
"Both these stores have a strong public commitment to source other meats from the UK. They must show the same commitment to pork."
The union said it would be requesting new industry intelligence on the availability of British pork next month.