The Irish Farmers' Association has accused Agriculture Minister Simon Coveney of conceding too much to the EU Commission during negotiations on the Common Agricultural Policy reform.
The EU Commission is seeking to move its single farm payment system from a method based on how much farmers produce to one based on a flat payment per hectare.
The IFA argues that this will reward farmers who do very little, while penalising farmers who are the most productive.
The association held an emergency meeting yesterday to discuss the matter.
IFA President John Bryan said the proposed changes could cause irreparable damage to the Irish agricultural industry.
Speaking on RTÉ's Morning Ireland, he said the proposed reforms mean that some farmers' incomes would be cut by up to 50%, while the average cut would be around 30%.
Meanwhile, Minister Coveney has said proposals to change CAP will make the system fairer for all farmers.
Speaking on the same programme, Mr Coveney said opposition from the IFA was not surprising as it wanted to maintain the status quo.
Mr Coveney said reform is badly needed.
He said his priority is to insure that productive farmers stay productive and are given the support to be able to grow and expand and produce more food.
Mr Coveney said: “It's my job to get the balance right for Irish agriculture and I'll do that."