Businessman Denis O’Brien enjoyed an interest rate of about 1.25 per cent on an IBRC loan when he “arguably should’’ have been charged 7.5 per cent, Independent TD Catherine Murphy has claimed in the Dáil.

“Given that we are talking about outstanding sums of upwards of €500 million, the interest rate applied is not an insignificant issue for the public interest,’’ she added.

She said it was known "Denis O'Brien felt confident enough in his dealings with IBRC that he could write to Kieran Wallace, the special liquidator, to demand that the same favourable terms, extended to him by way of verbal agreement, be continued''.

She said Mr Wallace, who had been appointed by the Government to conduct the IBRC review, joined with IBRC and Denis O'Brien in the High Court to seek to injunct the information she had outlined from coming into the public domain.

"Surely, that alone represents a conflict,'' Ms Murphy added.

The Kildare North TD was moving her Private Member's Bill, Comptroller and Auditor General (Amendment) Bill 2015, extending the functions and powers of the comptroller to cover IBRC.

Not within remit

She said it was Taoiseach Enda Kenny who first suggested the comptroller review the Siteserv sale, but it was pointed out to him that it was not within his remit.

“With this Bill, I am attempting to address that problem by broadening the remit of the Comptroller and Auditor General,’’ she added.

Ms Murphy claimed the Government had got the matter badly wrong.

"That is not least because most of the key players in the Siteserv saga have links with KPMG and the eventual purchaser, and vice versa,'' she added.

“It is a web of connections and conflicts that requires outside eyes to unravel.’’

Ms Murphy said a full commission of inquiry might be a better option.