At least three livestock dealers in Northern Ireland are at the centre of investigations into the movement of sheep before foot-and-mouth occurred in the North.
As Northern Ireland Department of Agriculture officials in Belfast widened their inquiry to all registered sheep brought into the North from Scotland since the New Year, it emerged investigators have been looking at the activities of several dealers including one in south Co Derry.
It is understood about 15,000 animals were imported into Northern Ireland between January 1st and February 21st before rigorous foot-and-mouth port controls were introduced.
Animals were bought from livestock markets in Longtown and Carlisle and imported legally into Northern Ireland from the Stranraer and Cairnryan ferry ports.
But it is alleged that although some were destined for meat plants, not all the animals were processed but were transported instead to farms in Northern Ireland and the Republic.
Democratic Unionist leader the Rev Ian Paisley tonight expressed "deep concern" at the widening of the investigation to sheep imported in January.
"There could still be sheep brought in that are being moved about the province. They could be leaving a trail of poison around the countryside as animals are moved to different farms," he said.
Earlier, the North's agriculture minister, Ms Bríd Rodgers, said: "There is a possibility of a link with illegal imports. There are other possibilities that we are looking at but we simply don't know. We are following everything up."
PA