It has been claimed the fine imposed on Northern Ireland by the European Commission over farm payments could end up substantially higher than £60m.
The warning has come in a joint statement from MEPs Diane Dodds and Jim Nicholson.
It is feared the final total of the fines could be up to £100m.
The money is likely to come out of the European block grant given to the Northern Ireland Executive.
The fines are a result of payments made in error to farmers in Northern Ireland from 2004-2008.
However, Mrs Dodds and Mr Nicholson said another fine is likely for the claim year 2008-2009 and because the Department of Agriculture has said the problem will not be resolved until next year, another fine could be imposed for 2010.
The EU has said the fines are a punishment and therefore are meant to hurt and have been imposed as a result of maladministration by the NI Agriculture Department.
The two MEPs met with senior EU Commission officials in Strasbourg this week to discuss the issue.
They said they would seek a meeting with Agriculture Minister Michelle Gildernew to discuss why action was not taken earlier to remedy deficiencies.
"We will continue to do all we can in Brussels to fight this, and will be requesting an urgent meeting with (Agriculture) Commissioner Dacian Ciolos," Mrs Dodds and Mr Nicholson said.
Annual claims are submitted to the Department of Agriculture and are supported by maps showing the farmer's fields and the crops which are grown.
In total, Europe provides 300m euros to farmers in NI annually while the individual subsidy claims are administered locally by the Department of Agriculture.
But when the European Commission sent in its team of auditors, they discovered many of the maps farmers had sent in were not accurate.
In some cases, fields had been built on but the maps which had been submitted showed the areas as prime agricultural land for which farmers were still claiming.
Another problem was that areas which farmers were declaring as grazing land were found to be covered in scrub, bracken and rushes.
However, the final straw for the EU is understood to have been instances where more than one farmer was claiming subsidies on the same piece of land.