Fears stolen Lincolnshire sheep may enter food chain
There are fears that meat from almost 1,500 sheep which were stolen in Lincolnshire could be sold for human consumption.
Trading Standards said the animals were likely to end up at unregulated abattoirs outside veterinary controls.
It could lead to a public health risk, the National Farmers Union (NFU) said.
The sheep were taken from a 40-acre field at Stenigot, near Louth, between Saturday evening and Sunday morning in a "highly organised" raid.
It is believed to be the largest theft of sheep in the country in the last 25 years.
Peter Garbutt, NFU chief livestock adviser, said: "The safety of illegal meat is highly suspect.
"We've no guarantees on the hygiene when these animals are slaughtered or the meat being prepared."
Ian Newell, from Lincolnshire Trading Standards, said: "These animals have been medicated and they were not outside their withdrawal period for the medicines.
"Farmers work with vets to make sure medicated animals don't get into the food chain."
There were 579 ewes and 901 lambs in the field, which were estimated to be worth £100,000 when the theft took place.
Mr Garbutt described the theft as "highly organised".
He said: "It's done by professional people who know what they are doing.
"They know they have a market for whatever they steal."
Tim Price, from NFU Mutual, said it was a concern that the thieves believed they had an outlet for the livestock.
"All sheep now have tags in their ears. They (thieves) must falsify documentation and their identities to get them in the food chain," he said.
"It's very worrying to think that that can be happening when all the regulations around food processing in the UK are very tight."
About 33,000 sheep have been stolen in England between January and August this year, police said.