The investigation into the sale of Siteserv to a company controlled by businessman Denis O'Brien has cost the State €19m, Taoiseach Leo Varadkar has told the Dáil.
The Irish Bank Resolution Corporation (IBRC) Commission of Investigation was established in early 2015 but only produced its report into the transaction in July 2022.
It concluded the sale of Siteserv in 2012 was "tainted by impropriety" from the perspective of the State-owned IBRC - formerly Anglo Irish Bank.
The bank wrote off €118m of a total of €150m it was owed by Siteserv as part of the €45m takeover by Mr O'Brien.
Today the Government received the final report of the commission.
Mr Varadkar said while costs of the investigation were being finalised "we expect it will be in the region of €19m including the cost of third party legal costs in respect of witnesses who appeared before it".
However he said the figure does not include further legal challenges which might arise.
The Commission of Investigation was originally tasked with examining more that 30 other transactions but the Government agreed with the recommendation from the investigation that to continue "would serve no useful purpose".
Aontú TD Peadar Tóibín said the investigation was supposed to cost €4m and ended up costing €19m.
He said in general investigations were "never ending" and costing the taxpayers millions of euro.
The Taoiseach said the Minister for Justice will consider suggestions for reform of the commission of investigation process.
He added when there are demands for investigations he tells people the probes will "take years", costing "millions of euro and you may not be happy with the outcome".
He added the new Corporate Enforcement Authority now has "stronger powers" to investigate "malpractice or fraud" and said it is the body that probably should be used to investigate commercial transactions.
In its report to Government today, the IBRC Commission of Investigation said it was now "impossible" to conduct investigations into matters of urgent public importance given in an expeditious manner while also complying with the requirements of fair procedures laid down by the courts.
It has recommended the establishment of a permanent commission of investigation with legal and IT resources.
It said there needed to be enhanced scrutiny of terms of reference of investigation to ensure they are confined to matters of fact.
It said that one of the difficulties faced by the IBRC investigation was that it received anonymous information from TDs.
The politicians were unable to reveal the identities of the people who provided documents.
It said in many cases the information was "not true or not true in substance".
The commission warned the Government that it should be very careful about establishing investigations which are based on information from anonymous sources.