Campaigners against the M3 said archaeologists working for the National Roads Authority have discovered another potential national monument in the path of the motorway.
According to TaraWatch two stone 'souterrains', or underground strutures, have been uncovered, 10 meters apart, approximately 80 meters northwest of the recently discovered henge in Lismullen.
The group said they learned of the site while inspecting excavations yesterday, after archaeologists went home and left the site unguarded.
Vincent Salafia of TaraWatch said they would be reporting the discovery to the Minister for the Environment John Gormley and the National Museum today.
"We want to know if the National Roads Authority reported the discovery to the Minister or the Museum, and if not, why not?," Mr Salafia said.