Independent MEP Kathy Sinnott has said work on the M3 motorway in Co Meath is illegal and should be suspended.
Speaking on RTÉ Radio's Morning Ireland, she said she had approached the European Commission about the motorway.
Ms Sinnott said she was told that under European law, this project needed an Environment Impact Assessment. She said such an assessment was carried out in 2003 on the basis then that there was no national monument in the path of the road.
She said the European Commission 'tagged on' Lismullen this year, and that its demolition required an assessment.
Also on the programme, Minister for the Environment John Gormley said he was taking a legal warning from the Commission about the M3 very seriously.
He said he would travel to Brussels tomorrow where he will discuss the matter. He said, however, that he did not have the power to re-route the entire M3, although he can deal with certain issues.
Mr Gormley said he had appointed a committee to conduct an archaeological review and released the Lismullen file.
He said he had written advice from the Attorney General that unless there was a material change of circumstances, he could not revise Dick Roche's decision.
