The operation to remove part of the medieval Carrickmines Castle site in South Dublin was stalled today following an illegal dumping of waste overnight.
It is understood that work on removing the castle's perimeter wall has had to be halted to allow for the clearing of fridges and other waste which were apparently left on the site overnight.
Dun Laoghaire-Rathdown Council say the work will continue as soon as possible and that a number of archaeologists are on the site.
The council plans to remove the ditch before beginning construction work on the South Eastern Motorway at the medieval site.
However conservationists have campaigned for the preservation of the archaeological site.
The High Court on thursday refused to grant an order preventing the removal of a section of an ancient fosse - a walled ditch - at Carrickmines, on the line of Dublin's South Eastern Motorway.