The US and British governments "lied to the world" before making war on Iraq and the Irish Government "swallowed their lies", the Labour MEP, Mr Proinsias De Rossa, has charged.
He told a news conference in Dublin that it was "essential" for members of the public to turn out in great numbers to march from Parnell Square to Government Buildings on September 27th, in protest against the US-led occupation of Iraq.
"The more people who protest, the more likely we are to have a sane policy implemented by the international community." He said the Government should use its position in the European presidency during the first half of 2004 "to unite the EU to work towards an agreed timetable for the withdrawal of the occupation and for the reconstruction and handing over of power to the Iraqi people under the authority and control of the UN".
The news conference was convened by the same loose alliance of peace groups which organised the big anti-war march on February 15th last.
Commenting on the situation in Iraq, the Green MEP for Dublin, Ms Patricia McKenna, said: "It was bad before but now it is even worse."
The Taoiseach and the Minister for Foreign Affairs should be "held accountable" for supporting the invasion of Iraq.
No weapons of mass destruction had been discovered and what did the Government have to say about this? "Brian Cowen and Bertie Ahern really have a case to answer here," she said.
Dr Andy Storey of the NGO Peace Alliance warned that the UN could be misused to "bail out" the Bush administration and legitimise the US invasion of Iraq. Irish troops should not be used for such purposes, he added.
Mr Roger Cole of the Peace and Neutrality Alliance said that the "US and its allies will be defeated as they were in Vietnam". He added that in the forthcoming European Parliament and local elections next June, people should vote "only for those candidates who support the end of the occupations of Iraq and Palestine".
He added: "On September 27th the people can march against Bush, Blair and Ahern's war. In June 2004 they can vote against Ahern's war."