Republican Sinn Féin is to campaign against the EU reform treaty when a referendum is held next year.
Party president Ruairí Ó Brádaigh said the treaty would create a supranational state making the EU separate from and superior to each of its member states.
"This would make the EU just like the United States of America in that the USA is separate from, and constitutionally superior to, California and New York.
"Similarly, Germany is separate from and superior to Bavaria and Saxony," he said.
Addressing his party's ardfheis in Dublin, Mr Ó Brádaigh said the treaty represented a new form of imperialism which would lead Europe into an oil grab and the resource wars of the 21st century.
The party would also organise politically against any planned visit by Queen Elizabeth to the Republic, he warned.
"The fawning - in a most servile manner - that we witnessed when the heir to the crown of 'Great Britain and Northern Ireland' visited Dublin in 1995 is bound to be repeated in nauseating fashion.
"For the very good reason that as Irish republicans we dispute the claim of the English crown to govern any part of Ireland, we must oppose politically such a visit - the first in 100 years - and organise politically against it. It is simply our duty to do so."
The campaign for political status for Continuity IRA inmates in the North's Maghaberry prison would also continue, he said, even though the prisoners suspended their protest after 10 months last May.
Delegates at the ardfheis voted to contest the next local elections in the Republic due in 2009 and to explore the possibility of contesting local elections in the North.
After some debate, delegates also voted in support of a motion reiterating the party's opposition to "broad political fronts which serve to dilute the national objective as expressed in the 1916 Proclamation".
Another ardfheis motion which called for the removal of the ban on political activities with other groups was not passed.
