The Minister for the Environment, Dick Roche, has ordered that some work be stopped in an area surrounding a prehistoric find on part of the planned route of the M3 motorway in Co Meath.
It follows the finding of what has been described as a substantial national monument at Lismullen, beside the Hill of Tara.
On Monday, the Minister for Transport, Martin Cullen, turned the first sod on the M3 motorway.
The archaeological site is said to be the size of three football fields.
The Department of the Environment has declined to state whether it has issued draft directions to the National Museum that the newly discovered national monument be preserved by record'.
TaraWatch, the group campaigning to have the M3 motorway re-routed, has claimed that such an order has been issued and will result in the monument being destroyed in a matter of days after a brief examination.
A spokesman for Minister Roche declined to say whether or not such directions had been issued to the Director of the National Museum Dr Pat Wallace.