The Government has been accused of abusing taxpayers' money and attempting to circumvent a Supreme Court ruling on referendum expenditure, by allocating €750,000 for the publication and distribution of an updated White Paper and second explanatory booklet on the Treaty of Nice.
The White Paper was introduced yesterday by the Minister for Foreign Affairs, Mr Cowen, who said it was important that people had the facts.
The Minister for Justice, Mr McDowell, said the effects of a second No to Nice could be "devastating".
Mr Cowen said the cost of producing the White Paper was "in the region of €100,000".
Publication and distribution of a shorter information guide for every household at the beginning of September would cost around €650,000.
The Green TD, Mr John Gormley, claimed the new White Paper was a "complete abuse" of taxpayers' money intended for propaganda purposes only.
He pointed out that a White Paper had been published last year and an information guide sent to every home before the first Nice referendum,
His party colleague, Ms Patricia McKenna MEP, said: "This is clearly another attempt by the Government to get around the McKenna judgment and use taxpayers' money to promote the Government's views on the Nice Treaty."
She claimed the Referendum Commission was "effectively gagged" following the last vote on Nice.
"This impartial body is now prevented from fulfilling its crucial role of providing the pros and cons on the Nice Treaty in a fair manner.
"Instead this money is now being used by the Government to produce literature which the public cannot trust," she said.
However, Mr McDowell told journalists: "There is simply no constitutional or democratic validity to the proposition that issues of constitutional change can only be put to the electorate once."
Several issues had been voted on more than once in the past. "On each occasion the people do have the final say for the time being, in relation to the proposition put before them, but on no occasion has it ever been suggested that one referendum precludes the holding of another," he said.
The prominent Eurosceptic campaigner, Mr Anthony Coughlan, said the Government was committing a "constitutional outrage" by holding a second referendum. "This is truly an awesome moment in our constitutional history."
Mr Coughlan added: "The extra clause inserted by the Government to the effect that we must have a referendum if we wish to join an EU defence pact has nothing to do with the Nice Treaty and is irrelevant spin-doctoring."
However, Mr Cowen said it was the Government's conviction, "based on the increased mandate we received in the last election", that the question should be put again for the sake of vital national interests.
Secondly, the "roadmap" for enlargement set out by the EU member-states required Irish ratification of the treaty by the end of this year.
Asked if there could be a third Nice referendum, he replied: "I don't envisage, nor do I look to, putting this question a third time."