No final decision on the ECB's plans has been made yet and Germany's Bundesbank is still seeking safeguards, including a likely move to make national central banks rather than the ECB bear much of the risk for buying the bonds of member states.

"If it is going to be renationalised and if monetary policy becomes a function of national central banks acting as agents for Frankfurt, I think it will be ineffective," Noonan told a conference.

(Reporting by Padraic Halpin; Editing by Kevin Liffey)