Following European Commission President Jose Manuel Barroso, European Central Bank President Jean-Claude Trichet has voiced sharp criticism of financial rating agencies.

Thursday Trichet spoke about the existence of a "structure of international credit agencies similar to an oligopoly," describing it as "highly undesirable."

What provoked the unusually sharp criticism was the Tuesday downgrading of Portugal's debt rating to "junk" on the part of Moody's, something that also provoked the ire of EC President Barroso.

Wednesday Barroso said the timing of the downgrade was "questionable" and raised the issue of the "appropriateness of behaviour" of the agencies in general, reported the BBC.

A Commission statement further characterized Moody's move as "an unfortunate speculation."

National leaders have also reacted to the events, with German Minister of Finance Wolfgang Schaeuble calling for limiting the influence of agencies on global financial life.

On his part, Greek Minister of Foreign Affairs Stavros Lambrinidis, whose country is also suffering severe financial troubles, described the downgrading of Portugal's ratings as "madness" that could lead to a "self-fulfilling prophecy."