Department of Environment officials will write to their counterparts in Britain today seeking clarification as to the volume and material contained within fluid which leaked from a pipe in Sellafield last month.
A spokesman for the Department said notification of a leak of highly radioactive nuclear fuel dissolved in nitric acid at the Thorp reprocessing plant was received on April 22nd.
However, this notification did not detail the volume or properties of the leaked material and further details are now being sought from Britain's Department for Environment Food and Rural Affairs.
The spokesman also said the Department was satisfied that the four-day period - which elapsed between the leak being discovered on the 18th and the Government being notificied on the 22nd - constituted a timely response.
Prompt reporting of safety issues at the plant is part of improved arrangements on nuclear matters agreed between Ireland and the UK last December.
The pipes and the container are in a sealed part of the plant and British Nuclear Fuels Limited (BNFL) says there has been no increase in radioactivity levels and that there is no health or environmental risk.
Dealing with the leak and recovering the liquids may require robots and could take months. The Thorp reprocessing plant had been due for a seven-week shutdown for maintenance but this is now expected to stretch to between three and six months.
BNFL has set up a board of inquiry to investigate how the leak occurred. A separate inquiry has been set up by the Nuclear Installations Inspectorate and this body has the power to prosecute if guildelines are found not to have been followed.
The Thorp plant reprocesses spent fuel and produces uranium and plutonium. Over the last 12 years Thorp has reprocessed 5,644 tonnes of fuel. Reprocessing at Thorp is due to end in 2012 but the plant will pose an environmental risk for the the next 150 years until finally decommissioned.
The Green Party said the leak highlights the need for the plant to close permanently.
Green Party environment spokesman Ciaran Cuffe said the leak, which he said was enough to fill half an Olympic-sized swimming pool, yet again underlines the danger Sellafield presents to Ireland.
Emmet Stagg, the Labour Party's spokesman on nuclear safety, also said the Government must intensify its efforts to have the plant closed.
"It now appears that the leak at the Thorp reprocessing plant on April 19th was far more serious than was indicated at the time and may have involved as much as 20 tonnes of uranium and plutonium," Mr Stagg said.
"The Irish Government must live up to its policy and begin working for the immediate closure of the plant. The consequences of failing to do so could be absolutely catastrophic for the Irish people."
Fine Gael's environment spokesman Fergus O'Dowd said that since the Minister was aware of the leak last month, he must make a full statement to the Dáil as to what steps he took at that time.
"The leak from a pipe in Sellafield last month once again illustrates the potential for environmental harm that this facility poses to Ireland," Mr O'Dowd said.
"While I accept for the moment that there is no health hazard, clarification is needed on the volume and material contained within the fluid that leaked from the pipe."
In a statement this evening, Mr Roche said statements issued today suggesting that Ireland had not been notified of the leak by the British authorities were "factually incorrect and misleading".
A press release issued by his department in April "confirmed that Ireland was advised promptly of the incident, that there was no abnormal activity in the air and therefore no risk to employees, to the local community or the environment".
"Based on the information received it was clear that the incident had no implications for Ireland. This information received in relation to this serious incident was obtained as a direct result of the Government's ongoing legal and diplomatic offensive regarding the continued operation of Sellafield."