Bodies such as Fitch, Standard & Poor's and Moody's have all been registered as official ratings agencies with the EMSA, which means they have agreed to be supervised in their operations.
In an attempt to make the system fairer and more transparent, the EMSA will conduct investigations of all firms involved to make sure they are acting properly and within the constraints of the law.
Steven Maijoor - chairman of the independent arm of the European Union - commented that this represents a "major step towards a sounder credit rating market" in Europe in the aftermath of the global economic downturn.
"By supervising these entities, ESMA will contribute to the quality of ratings, which is crucial for the well-functioning of financial markets and investor protection," he added.
By Asim Shah