The agriculture and food services industry in Northern Ireland could be jeopardised if the scale of illegal meat production increases, Health Minister Edwin Poots has warned.
But Edwin Poots said factories uncovered in counties Armagh and Down this week did not represent a large operation and should not be blown out of proportion.
A suspected illegal animal slaughterhouse and meat cutting plant was found in the Newry and Mourne area, allegedly without official hygiene checks, the Food Standards Agency (FSA) said.
Investigations are ongoing into what businesses the produce was sold to.
Mr Poots said: "People who are aware of these activities can and should report it to the authorities, and consequently that can be followed up.
"Individuals engaging in this type of activity are jeopardising the agriculture and food services sector."
The Police Service of Northern Ireland (PSNI), Stormont's Department of Agriculture and Rural Development (DARD) and Newry and Mourne District Council are involved in the investigation.
Mr Poots told the Stormont assembly: "Even though it can be a very small thing that is happening, on the scale of the number of cattle killed in Northern Ireland every day, this is not positive news for Northern Ireland.
"It is very unfortunate that some ne'er-do-wells are prepared to compromise the Northern Ireland industry in such a way."
A tenth of people in Northern Ireland are employed by the food industry.
The minister added: "We cannot afford for this industry to be dragged down by criminal elements from one particular area that keeps popping its head up over and over again."
He appealed for people to buy their meat from reputable sources, not off the back of a lorry, but said in most cases they could have absolute surety that the meat they were buying was of the highest quality.
Police said searches of two properties in Forkhill and one in the Bessbrook area were conducted.
"A suspected illegal animal slaughter and meat cutting operation was discovered," said a PSNI spokeswoman.