Michel Barnier made the comments to the European Parliament after he expressed surprise at the speed at which the ailing stateâs rating was downgraded to âjunkâ.
The commissioner suggested that he was considering setting up an EU agency to rate the credit of governments in the territory.
Mr Barnier said: âI think we need to go further to look at the impact of the ratings on the financial system or economic system as a whole.â
âThe power of these agencies is quite considerable not only for companies but also for states. That's why I asked for responsibility to be assumed in the work they are doing,â he added.
A new set of rules surrounding credit agencies and how they make decisions relating to downgrades is due to come into force in December of this year.
Meanwhile, the European Commission is to delay the introduction of the Solvency II framework until the end of December 2012.
The legislation has been postponed to align it with the start of the financial year for many European insurance firms.
By Jim Ottewill