The EU has called for a ban on rating agency decisions on countries under internationally-approved rescue packages.
Speaking in Brussels, Internal Markets Commissioner Michel Barnier also said that governments should be fully informed before being downgraded by ratings agencies.
'When a country belongs to the European Union and benefits from the solidarity of its members, when it follows a programme of international aid, one cannot refuse to take this into account,' Mr Barnier said in a speech.
Rating agencies came under heavy EU fire last week after Moody's downgraded Portugal's rating to 'junk' status, casting new doubts on the markets over EU efforts to manage the euro zone debt crisis.
Europeans were particularly angry over the timing of the ratings cut, issued just as Portugal begins to implement tough austerity measures in return for a €78 billion EU-IMF bail-out agreed in April - and as the euro zone struggles to craft a new rescue package for Greece.
European Commission president Jose Manuel Barroso said that the downgrade signalled an anti-European bias and suggested it was time for a European ratings agency to emerge as a counterweight to the US-dominated groups.
Earlier, the president of the European Council, Herman Van Rompuy, called an emergency meeting of key players to discuss the continuing euro zone debt crisis, ahead of a gathering of finance ministers this afternoon.
Mr Van Rompuy discussed the debt crisis with the president of the European Commission, the EU Economic and Monetary Affairs commissioner, the president of the European Central Bank and the chairman of the euro zone finance ministers.
Unsuccessful efforts to find a mechanism for private investors to contribute to a second bail-out for Greece have now been overshadowed by worries about the rising cost for Italy to service its public debt.
Today and tomorrow finance ministers will once again labour over ways to arrange some kind of private sector burden-sharing for a second Greek bail-out without triggering a wholesale default.
Greek deficit grows
Adding to the pressure for an agreement Greece's finance ministry today announced that the country's budget deficit grew by 27.9% in the first quarter of 2011.
Despite over a year of austerity efforts Greece's finances were over €2bn adrift with a recorded shortfall of €12.8bn, over a targeted €10.4bn.
Fiscal revenue was down by 8.3% compared with the same period last year while expenditure has increased by 8.8%, the ministry added.
