"I see it as reflecting an obsession to challenge the rating process itself, and to hold rating agencies responsible for the European debt crisis," Michel Madelain said.

"These proposals cannot make investors confident again nor facilitate the access of companies and European states to credit markets," he added.

The European Union earlier unveiled plans to shake up credit rating agencies, although it shelved for now a divisive move for temporary "blackouts" on some sovereign ratings.

EU financial services chief Michel Barnier said his draft law would inject competition into a sector dominated by three companies, Moody's Standard & Poor's and Fitch Ratings who warned the rules would leave investors with less choice.

Many EU policymakers want tougher rules for the sector, saying a ratings downgrade of Greek sovereign debt last year made it more expensive to mount the country's first bailout.