IBRC chairman Alan Dukes wrote to the Minister for Finance Michael Noonan in an attempt to counter media coverage which he said was "damaging and unhelpful" to the bank.
He was referring to the appointment of a Department of Finance official, Neil Ryan, to fill a senior role in IBRC. The bank was formerly Anglo Irish Bank.
It was speculated in the media that Mr Ryan's appointment could undermine the role of chief executive Mike Aynsley and his team.
That prompted Sinn Fein leader Gerry Adams to ask Minister Noonan in the Dail if he had confidence in IBRC's board and executives.
Last month Mr Noonan confirmed his confidence in the board and management in a written reply.
In his letter in October, Mr Dukes says: "of significant concern to me as chairman of the bank is that the question also requests that you confirm your continued confidence in the management and board of the bank."
In the letter released to RTE News under Freedom of Information, the bank's chairman Alan Dukes said media coverage of Mr Ryan's appointment had affected the bank's reputation "internally and externally."
He added: "Essentially, the positive message of Neil's future contribution to the bank was tarnished due to misplaced media commentary."
Mr Dukes said the bank's CEO Mike Anysley had countered the reporting on Mr Ryan's appointment internally.
Mr Dukes said Mr Ryan's skills and experience represented an important contribution to the bank.