The European Central Bank threatened to cut off emergency funding from the Irish banking system in November 2010.
The threat is contained in a letter - which was marked 'secret' - from then ECB President Jean Claude Trichet to the late former Finance Minister Brian Lenihan, which has been obtained the Irish Times.
The letter, which was sent on November 19 2010, says that unless Ireland applied for a bailout from the EU and IMF before that weekend was out, all ECB emergency funding to banks would have been cut off.
Ireland formally applied for the bailout two days later, on November 21.
The publication of the letter in the Irish Times comes ahead of an expected discussion at the ECB's monthly meeting on whether it will release the letter later today.