The European Central Bank (ECB) exceeded its mandate by taking on political powers during the eurozone crisis, according to a report by anti-corruption watchdog Transparency International.
The ECB's role in the Greek, Irish and Portuguese bailouts has long been controversial, not least in then ECB president Jean-Claude Trichet's secret letters to the late Brian Lenihan demanding the Irish seek a bailout in 2010.
The report said the ECB strayed into the area of political decision-making, without appropriate democratic scrutiny. The report called for greater transparency and said the ECB should no longer be part of the Troika.
The report said that the ECB needs to better engage with the public, if it is to ensure support for the euro.
If the ECB wants to preserve its cherished independence, it can't hide behind a technocratic image, the report said.
In a statement, the ECB said steps had been taken since the crisis to "further enhance its transparency, accountability and integrity mechanisms".
"The extraordinary measures taken by the ECB since 2008 have tested the ECB's mandate to breaking point," Transparency International EU said.
The report said euro-area politicians, not the ECB, should sign off on any monetary deal for countries that comes with conditions.