Minister for Finance Michael Noonan has confirmed his department conducted a review of IBRC's involvement in a deal which resulted in engineering company Siteserv being sold to Millington, a firm controlled by businessman Denis O'Brien.
In the course of the transaction, €100m of Siteserv's debts to IBRC were written off but Mr Noonan said he had been assured the deal was the best result for the State.
The minister said his officials "were made aware of certain aspects of the transaction which raised concerns with some of the quality of some of the decisions taken in respect of the transactions".
Among these concerns were the fact that law firm Arthur Cox had acted for the purchasers and vendors in the deal and that payments were made to the shareholders in Sitserv.
Mr Noonan, responding to a question from Independent TD Catherine Murphy, said he met IBRC chairman Alan Dukes and CEO Mike Aynsley concerning the transaction.
Mr Noonan said he was told legal advice was provided by two different teams within Arthur Cox and "appropriate Chinese walls were in place between the two teams".
He added he was also assured the payment to shareholders was necessary to ensure a vote in favour of the deal.
He said he was assured the transaction was managed to achieve the best result for the State.
Siteserv Holdings said the transaction was conducted in full compliance with best corporate practice.
It also alleged that Catherine Murphy had made "repeated unfounded public accusations" regarding the transaction.
It said since the deal meant employment in Siteserv had grown from 1,635 in 2012 to 3,367 today.
However, Ms Murphy said "my agenda is always to serve the public interest and this deal involved a significant amount of money being written off. This is very firmly in the public interest."