The Minister for the Environment, Dick Roche, has said the State will continue to pursue legal action aimed at closing the Sellafield plant despite a setback at the European Court of Justice.
Ireland had hoped to bring Britain before a United Nations tribunal using the UN Convention on the Law of the Seas, but the European Court's legal adviser recommended EU institutions deal with the matter.
The legal adviser also said Ireland breached protocols by its action and had failed to fulfil its European treaty obligations.
This recommendation will come as a blow to the Government's international legal bid to close Sellafield, which the European Court of Justice is expected to deliver a determination on later this year.
However, the expectation now must be that Ireland will lose the case, given that the court accepts the recommendation of its legal advisor in 80% of cases.
Mr Roche said if the court rules it does have exclusive jurisdiction and the UN avenue is closed off, then he expects the European Commission to take robust action on Ireland's concerns over Sellafield.
Minister Roche maintained this was something the commission had not been doing to date and said Ireland would continue to pursue every diplomatic and legal option to secure the closure of Sellafield.