More than 2,000 jobs in the pig processing industry have been put at risk by pig farmers who are selling their produce to factories in Northern Ireland.
Mr Tom Walsh, assistant national executive officer of SIPTU, said: "The pig producers are switching supplies to the North of Ireland where they are getting more money for them and already there have been cutbacks of between five and 24 hours in production in some plants here."
Last night, the Minister for Agriculture, Mr Yates, said he would be examining the issue in light of the Single Market regulations.