Eleven euro zone countries have agreed to push ahead with a tax on their financial transactions, an initiative that several other EU nations oppose.
The number exceeds the threshold of nine needed to push ahead with initiative. The European Commission says it is ready to proceed with legislative proposal.
The breakthrough was a surprise to those who had thought Germany might fail to convince sufficient countries to join the plan, which was drawn up over two years.
Leaving a meeting of EU finance ministers in Luxembourg, Mr Noonan said that Ireland would not support a Financial Transactions Tax (FTT) so long as it was not supported by the UK.
He said there were 33,000 jobs in the financial services industry and some of those would be lost if Ireland introduced the tax and Britain did not.
Spain and Italy agreed at a meeting of EU finance ministers in Luxembourg that they would support the measure.
Slovakia and Estonia said they would throw their weight behind it too.
The proposal had already been formally backed by Greece, Portugal, Austria, Slovenia and Belgium as well as Germany and France.
That raised to 11 the number of EU countries prepared to push ahead with the proposal, exceeding the threshold of nine required under EU law to move ahead with legislation using a process called "enhanced cooperation".
Once nine of the countries have formally notified the European Commission, the EU executive and the body charged with proposing legislation, of their commitment in writing, the Commission will begin drafting the law. At the moment it is unclear how much the tax might raise, or how it would be spent.
Within the euro zone, Finland, the Netherlands and Ireland have strong reservations, and outside of the single currency group, Sweden is a vocal opponent of a tax it attempted to impose in the 1980s, only to see much of its trading shift to London at heavy cost.
"We still think that the financial transaction tax is a very dangerous tax," Finance Minister Anders Borg said ahead of the meeting. "It will have a negative impact on growth."
Britain, home to the region's biggest trading centre, has a stamp duty of 0.5% on share trades, raising almost £3 billion in the financial year to April 2011. It will not join the scheme and has lobbied Cyprus to stay out as well.
