According to the response, holdings of Greek sovereign bonds acquired under its Securities and Markets bond-buying programme (SMP) had resulted in €7.8bn of net income interest between 2012-2016.
These profits – as with others made from national bond holdings – are then redistributed to all 19-country central banks in the eurozone.
The SMP programme was launched at the start of the eurozone’s debt crisis in 2010 and ramped up to include Italian and Spanish government debt in 2011.
It was designed to ease market pressure on the borrowing costs of the eurozone’s member states and preceded the central bank’s more ambitious quantitative easing programme, which launched in 2015.
News of the billions of euros in profits are likely to anger hardliners in the Greek government who have long urged the ECB to allow Greece into the central bank’s current QE package.
The SMP profits have been promised to Greece at various points during its seven years of financial rescues.