The cabinet has agreed to set up a Commission of Investigation into the handling of certain transactions by IBRC.
Michael Noonan has said that there is no evidence of wrongdoing in any transaction, but he wants a report before the end of the year.
IBRC and its handling of some transactions - including the sale of SiteServ to a firm controlled by Denis O'Brien - were already being examined by IBRC's liquidators from KPMG.
But in the wake of Catherine Murphy's allegations, that Denis O'Brien paid a lower interest rate than other customers, that is now being scrapped in favour of a full independent Commission of Investigation.
Michael Noonan has said that there is still no evidence of any wrongdoing at IBRC, but that there is now enough public concern to merit a full inquiry.
Earlier sources explained that the inquiry by KPMG would no longer have public confidence, because nobody would believe it if it gave IBRC a clean bill of health.
But in the light of the High Court ruling in Denis O'Brien's injunction case against RTE, and the details it reveals, it is now possible that the actions of liquidator Kieran Wallace could also end up being examined.