Campaign group Tarawatch launched a petition today, claiming that there has been a number of changes to the situation at Tara since the former Minister signed the order.

They say work should at least be temporarily stopped pending a review, as the Hill of Tara has now become one of the most endangered sites.

The Environment Minister John Gormley, however, said he has tried everything - but it's just not possible.

"Unfortunately, there is contract in place, so you're into legal difficulties, you're into factual difficulties and at this stage, unfortunately, I don't think it is possible," he said.

"I've looked at all the legal possibilities, and the [Attorney General] has advised that it isn't possible."