The Government is trying to mobilise international support to stop two ships carrying nuclear material from passing through the Irish Sea on their way to Sellafield.
The Minister for the Environment, Mr Martin Cullen called the shipment "totally unacceptable to the world at large and the international community".
"There are two legal cases running, and what Ireland has to do now is bring on board the international community on this. The world has got to ask have we got to get involved in these hugely dangerous shipments moving around the world?" he added.
The controversial shipment of MOX - a potentially weapons-usable mixture of plutonium and uranium oxides - left Japanese waters today tracked part of the way by Greenpeace ship the MV Arctic Sunriseon its journey to Britain.
The ship, the Pacific Pintail, will be escorted by a sole transport ship the Pacific Tealand is expected to sail through the Irish Sea at the end of its six-week voyage.
It left Japan defying protests from anti-nuclear activists who warn it is a huge security risk. "The ships are slow, lightly armoured, and vulnerable to attack" a statement from Greenpeace said.
"The plutonium contained in this one cargo is sufficient for 50 nuclear weapons, if stolen" it added.
The shipment comes just days after the US state department warned of the potential for terrorist attacks on US Independence Day.
The state-controlled firm, British Nuclear Fuels limited (BNFL), agreed to take back the shipment following a controversy in 1999 when Kansai Electric discovered that BNFL had delibrately falsified data on the MOX consignment.
British government officials later apologised and BNFL agreed to take back the shipment and pay £40 million in compensation.
