Work will begin later today on the mass cull of thousands of sheep on farms between Meigh, Co Armagh and Proleek, Co Louth, where the two outbreaks of foot-and-mouth disease have been confirmed.
The joint operation, involving staff from both the Departments of Agriculture in the Republic and Northern Ireland, will create a sterile corridor between the two farms which lie on different sides of the Border.
The Northern Ireland Minister of Agriculture and Rural Development, Mrs Brid Rodgers, said her Department would be slaughtering around 2,000 sheep in the three-kilometre zone around the Meigh farm which would leave a corridor free of sheep to the northern side of the Border.
A similar announcement was made by the Minister for Agriculture, Food and Rural Development in the Republic, Mr Walsh, who said the cull around the Proleek farm would be extended north to the Border to create the corridor.
Mr Walsh said the joint initiative taken with the Northern authorities was for the purpose of eradicating any virus which may be present in the sheep populations in the areas where the two outbreaks occurred.
Mr Walsh said he could not specify how many additional sheep would now be culled but some of his officials estimated it could be upwards of 20,000 because it will also include farms adjacent to commonage on the Cooley mountains.
He also said Army marksmen will be called in to cull another source of potential spread of the disease, wild goats and deer which frequent the area.
There was apparent confusion yesterday between the two Departments of Agriculture, North and South, over tracing 60 "missing" sheep. Mrs Rodgers said the sheep, which had been imported into Northern Ireland from Britain, had been slaughtered in the Republic. Mr Walsh said 1,200 animals slaughtered on farms in Wexford, Meath, Laois and Carlow over the weekend on information from Northern Ireland might or might not have included the missing sheep.
He said the position of the sheep could not be resolved because of lack of identification as a result of there being no tags on the animals.
Meanwhile, an allegation by the French Minister of Agriculture, Mr Jean Glavany, that a consignment of Irish sheep caused the second outbreak of the disease in France was denied by Department of Agriculture officials in Dublin last night.
A Department spokesman said the Irish sheep mentioned by the Minister had been in contact with either sheep from Britain or a lorry in which contaminated sheep from Britain had been carried.