The ECB has refused to hand over a copy of the letter which forced Ireland into a bailout.
It has been confirmed that the bank's governors are refusing to release the letter written by Jean-Claude Trichet to Brian Lenihan in November 2010.
It i's alleged that Mr Trichet threatened to pull funding from Ireland's banks unless the Government accepted a bailout.
The ECB has said it is not in the public interest to release the letter.
Its decision has been criticised by the European Ombudsman Emily O'Reilly, who says she is unconvinced by the ECB's explanation.