The Peace and Neutrality Alliance (PANA) is to stage a demonstration march in Dublin city centre on 27th September protesting at American foreign policy in Iraq and Afghanistan.
The group is calling on the Irish Government to end the practice of US planes assisting in the war effort being allowed to use Shannon airport.
PANA, which organised the mass demonstration in Dublin in February that attracted over 100,000 marchers, is also campaigning for an end to the Israeli-Palestinian conflict.
A spokesman for the group, Mr Richard Boyd-Barrett, said the stated aims of the Bush administration at the outset of the conflicts in both Iraq and Afghanistan had failed to materialise.
In both countries a "tragic situation" now exists which is worse that the terrorist attacks of the World Trade Centre on 11th September, 2001.
"George Bush said the response to the terrorist attacks would end terrorism and would lead to a more peaceful and democratic world," he said.
"There now exists a situation in Afghanistan where US control does not "stretch beyond" Kabul. In all other parts of the country war lords, worse than the Taliban, now rule." Mr Boyd-Barrett added more than 7,000 Iraqi civilians were killed during the war, and estimates had put the current civilian daily death toll at 15 in Baghdad alone.
Mr Roger Cole, chairman of PANA, said by allowing US planes to use Shannon, the Irish Government had "collaborated and participated" in an "illegal war of conquest" in Iraq.
"This march will give another opportunity to those who wish to express their opposition to Bush, Blair and Ahern's war through taking part in a peaceful demonstration and we urge people to attend," he said.
The march will begin at the Garden of Remembrance, Parnell Square, at 2 p.m. on 27th September, make its way across town, and finish with a rally outside Government Buildings on Upper Merrion Street.
