The Irish Farmers' Association wants a closer inspection and tighter controls on the importation of lamb from Northern Ireland by meat factories in the State.
These imports, said Laurence Fallon, chairman of the IFA's national sheep committee, had reached huge volumes and were driving down the prices paid to farmers in the State.
"So many lambs are being imported that we are beginning to wonder where they are coming from," Mr Fallon said. "We want tighter monitoring of these imports because, if for no other reason, it was this trade which brought us foot-and-mouth disease in 2001."
By using imports to depress prices paid to Irish farmers, the factories were driving producers away from feeding hoggets at this expensive time of year, he said.
Figures from An Bord Bia at the weekend showed a decline of over 6 per cent in the national sheep flock last year. The board published CSO figures which showed that the breeding flock in the State had declined by almost 210,000 to 3.57 million head.
"This reflects the increased level of cull ewe slaughterings, which were over 24 per cent, or almost 90,000 head, above 2003 levels," the Bord Bia weekly monitor report stated.
"Within the breeding flock, ewes over two years declined by 88,000 head, while ewes under two years were down 17 per cent, or 120,000 head, reflecting the lower retention of ewe lambs for breeding in 2005," it added.