The Government is expected to make a robust defence of its excavation of the archaeological sites at Tara, to the European Commission this week.
It follows a written warning from the Commission over the demolition of the national monument at Lismullen, which lies in the path of the planned M3 motorway in Meath.
Commissioner for the Environment Stavros Dimas wrote to the Government asking why a second impact assessment was not carried out when the Lismullen site was discovered.
The Government is rejecting claims that it should have carried out a new environmental impact assessment at the site, as required under the National Monuments Act.
Fianna Fáil MEP Liam Aylward is also disputing speculation that Ireland could face large fines if it's found to have acted illegally.