Rees Roberts, chairman of HCC Meat Promotion Wales, said: "Farmers in Wales are suffering from low lamb prices right now and that's largely because supermarkets are too rigidly adopting a seasonal buying policy that favours imports."
"It's become as inevitable as autumn follows summer- when the temperature drops, lamb prices drop.
"It's not just the farmer's lobby that's saying this - research shows that consumers want our retailers to act responsibly, support local food producers and not benefit those who are based thousands of miles away and leaving significant carbon footprints behind," he added.
Last January saw the largest lamb price drop in the whole of 2006, he said, with Welsh producers witnessing an 11% fall in prices.
"These figures paint a grim picture - well before Christmas the supermarkets are pulling down the shutters on British Lamb and opening the back door to imports- at great cost to our farmers, our rural communities and the environment," Roberts said.