SIPTU says around 900 workers have been laid off at four pig-meat plants in Offaly, Leitrim and Tipperary this morning as a result of the dioxin contamination scare.
The union says up to 6,000 jobs are at risk in the pig industry following the removal of Irish pork and bacon from sale across the world.
It is criticising the stringent measures implemented by the Government and the Food Safety Authority, claiming they were too stringent given that only a minority of pig farms were affected by the contaminated feed.
The Irish Farmers Association, meanwhile, says it is impossible to estimate how much the contamination scandal will cost the Irish pork industry.
Association president Padraig Walshe is due meet processors and the Minister for Agriculture this afternoon to discuss the crisis, with some estimates putting the total cost at around €1bn.