An Bord Pleanála has intervened in the dispute about the building of the M50 motorway through the archaeological remains of Carrickmines Castle in south Dublin.
The board has given Dún Laoghaire/Rathdown County Council until the end of this week to provide information regarding the choice of route for the south-eastern leg of the M50.
Protesters say the route originally chosen for the motorway in the early 1990s was replaced by a new route which passes through the medieval remains of Carrickmines Castle.
The board now wants to know why the decision to change the route was made and whether this constitutes a material change to the permission to build the motorway.
It is acting on foot of a complaint by a local An Taisce member, Mr Stephen Devaney, who argues that the change is a material one and therefore requires the conducting of a new Environmental Impact Study.
A board official confirmed yesterday it had requested information from the local authority, but she stressed that no decision had been made to carry out a formal investigation.
However, if the board decides to examine the matter in detail, all works on the south-eastern leg of the motorway would have to stop, the official confirmed.
Under new powers conferred on the board by a recent Roads Act, it is entitled to give a direction indicating whether an EIS is required for any road scheme.
The council insists the motorway planning was carried out fully in accordance with statutory procedures.
A local PD councillor, Mr Victor Boyhan, has called on the county council to "bend" the proposed route around the site by shifting the line of the motorway slightly to the south.
"Let's put our heads together, move the route while still keeping it on council lands, and get on with it," he said.
Conservationists styling themselves "Carrickminders" have been attempting to block initial works on the motorway during the past few weeks.
They say up to 80 per cent of the site will be obliterated by the motorway and ancillary works.
The Minister for the Environment, Mr Brennan, has given the go-ahead for construction, although he admitted he was "not comfortable about it". He estimated that more than 60 per cent of the site would be saved, and some structures would be dismantled and reconstructed elsewhere.
The Carrickmines site was excavated for two years at a cost of €6 million before the go-ahead for building the M50 was given.
The dig revealed some of the defensive elements of the castle and associated industrial and habitational areas, but the physical remains of the castle itself were not found.
