The Government has pledged to immediately halt illegal dumping by the State's national heritage service Dúchas at a site in south Tipperary.
The Minister of State at the Department of the Environment, Mr Noel Ahern, said he deeply regretted that Dúchas had disposed of materials, mainly construction materials, at the site.
"There won't be anything else dumped in that place. That will stop immediately," he said. "We will cooperate fully with the authorities to see how it has been happening and why it has been happening".
Dúchas ordered an internal investigation into how a truck from Kilkenny city deposited waste at a site outside the village of Killenaule. Tipperary County Council also ordered an inquiry.
Mr Ahern said it was hard to imagine why anybody would want to dump waste in such a way.
"We are trying to change the habits of the nation and there is a gap between passing legislation and getting people to change their habits and change their culture".
The matter was raised last night in the Dáil by Fianna Fáil TD for Kilkenny, Mr John McGuinness.