The Tanaiste has denied that the EU would replace Ireland's national corporation tax rate with EU tax harmonisation followinga "Yes" vote.
In a statement issued this afternoon, Ms Harneyalso denied claims by the "No to Nice" campaign that the implementation of the Treaty will meanthe loss of Irish jobs.
"The rules on enhanced co-operation in the Nice Treaty explicitly provide that no country can be forced to take in those policies, and no country can be kept out of participating either," Ms Harney said.
"If a group of EU countries want to go ahead with harmonised taxes among themselves, they'll be perfectly entitled to do so. But they can't impose that on any other country".
Ms Harney also claimed the No campaign's open hostility to foreign companies threatened the 300,000 jobs these companies provided in Ireland.
