The European Commission has described Moody's decision to downgrade Ireland's debt to junk status as 'incomprehensible'.
Meanwhile, Taoiseach Enda Kenny has told the Dáil that it is time for Europe 'to grasp the nettle' and set out a comprehensive response to the financial crisis.
Mr Kenny said the latest revelations about Italy's debt of €1.8 trillion was a cause of concern.
In a statement, European Commission President Jose Manuel Barroso said the Irish Government had shown 'determination and decisiveness' in its implementation of the economic adjustment programme.
Moody's decision was earlier criticised by the Department of Finance.
A spokesman for the department said it was completely at odds with recent views of other credit rating agencies.
Speaking on Morning Ireland, Minister for Enterprise, Jobs & Innovation Richard Bruton said the move was due to the overall debt situation in the eurozone.
The downgrade immediately prompted the euro to fall against the dollar.
Moody's said it took the decision because Ireland was likely to need a second bailout.
It indicated private investors would have to suffer some losses ruling out a return to the markets.
It said while there had been strong commitment to consolidation, there was continued weakness in the economy.
The spokesman for the Department of Finance said there was no reason for Moody's to downgrade Ireland.
He added it was difficult to see how the decision reflected the agreement of eurozone ministers on Monday.
The National Treasury Management Agency said Ireland had sufficient funding to cover requirements until the end of 2013.
Authorities pointed out Ireland had not been downgraded by other rating agencies, which is something they hope will not change.