Lamb rustling has rocketed by 250% in the last year as thieves increasingly target mouth-watering black market profits.
The public's taste for tender Welsh lamb, at knock down prices, is among the factors fueling the rise in illicit sales.
Officers with the Welsh Food Fraud Co-ordination Unit say they are looking at more cases of illegal meat sales than ever before.
They range from illegal slaughtering to door-to-door salesmen offering boxes of meat to households, said unit manager Rob Phillips.
As a result the amount of illegal lamb's meat in the food chain has soared by as much as 250% this year, it claims.
The startling statistic is contained in an article in the current edition of The Grocer, the business magazine for the food and drink industry.
Rural insurer NFU Mutual had received claims for more than 60,000 stolen sheep by the end of October - two-and-a-half times more than last year, it says. Cattle, pig and game rustling have also gone up over the period.
"We're concerned we could see further increases in crime as thieves see opportunities to steal livestock for the Christmas market," an NFU Mutual rural affairs spokesman told The Grocer.
"It's a big concern that stock may be slaughtered, butchered and stored in unhygienic conditions, putting the livestock industry at risk and spreading disease,"the NFU Mutual spokesman added.
Anthony Sturge, who runs a catering business and farmer's market stall from his Brighton base, said he had been approached three times by a man who offered to sell him a whole lamb for £55, well below the market rate, without a receipt. "I personally haven't taken any because I need full traceability for my products, but I can see that if someone knocked on your door and offered it, you're not going to ask questions." he said.