More than 1,000 police and troops are manning entry points to the State and hauliers moving livestock are now required to have permits following further measures aimed at preventing foot-and-mouth disease entering the country.
Churches are being urged to provide disinfectant mats while mass in the areas around the contaminated farm in Co Armagh and a farm under investigation in north Co Louth has been cancelled.
After visiting the border operation with Garda Commissioner Pat Byrne, the minister for Agriculture Mr Walsh said: "We are on a virtual war footing here - and on full alert. Everything humanly possible has to be done to keep out this disease from Ireland.
"The effectiveness and the comprehensiveness of the controls in Ireland are more severe and widespread than in any other European Union member state, including the United Kingdom.
"Even though we have no evidence of any symptoms or clinical cases of foot-and-mouth whatsoever in any part of the Republic, we are treating the situation as if we have."
Claims that that smugglers are moving animals across the border have been rejected by the Ministers for Agriculture in the North and the Republic.
However, the Minister for Agriculture in Northern Ireland Mrs Bríd Rodgers said she is concerned that undetected livestock had recently been imported in to the North.
"I have also reason to be worried about several other imports from Scotland to Northern Ireland of livestock which may have been in contact with infected animals," she said.
There have also been claims in Northern Ireland that sufficient guards against the spread of the disease are not being taken.
Last night, RTE's Prime Time programme showed vehicles moving freely around the area where the infected sheep were discovered. A 3km exclusion zone has since been implemeted around the farm.
A farm in Dromin, Co Louth, remains sealed off this evening following fears a number of sheep at the farm may have come in contact with infected animals found at the contaminated farm in Co Armagh.
Three farms near Carrickmacross, Co Monaghan also remain cordoned off this evening.
A processing plant in Co Kildare is also under inspection and production has been halted at the plant, which employs hundreds of workers.
A Department of Agriculture spokesman said that they had received a number of calls from farmers and others associated with livestock, reporting sick animals or livestock that have come in contact with animals from Britain and Northern Ireland.
The Department are investigating all these cases "purely as a precautionary measure," the spokeman said.
"It can't be stressed enough that there are no cases of foot-and-mouth comfirmed in Ireland.
In Northern Ireland, officials are awaiting samples from six sheep showing symptoms on a farm in Castlederg in Co Tyrone.
The Northern Executive will hold an emergency meeting today to be briefed by the Minister for Agriculture Ms Brid Rodgers.