AN Irish government inquiry into the £1.24 billion Project Eagle sale - the biggest property deal in the north's history - will investigate if dealings between Stormont and Dublin leaders were appropriate.
The commission of investigation will probe the controversial sale by the Republic's toxic assets agency Nama.
The massive collection of Northern Ireland property loans, taken over by Nama after the economic crash, was sold to US investment fund Cerberus in April 2014.
A criminal investigation and parliamentary probes on both sides of the border were launched last year following claims about the sale.
It was alleged in the Dáil that a £7 million offshore fund linked to the deal was earmarked for a northern politician or party.
Another US company Pimco - a leading bidder - has said it pulled out of the sale because it was asked for a fixer payment of £16m for three parties behind the scenes.
The money was allegedly to be shared equally by businessman and former Nama Northern Ireland adviser Frank Cushnahan, US law firm Brown Rudnick and Ian Coulter - a former managing partner of Belfast solicitors Tughans.
All parties have denied any wrongdoing.
The deal was "seriously deficient", the Dáil's Public Accounts Committee concluded earlier this year after a long-running probe.
A report by Comptroller and Auditor General Seamus McCarthy also found Irish taxpayers lost up to €200m (£168m) on the sale.
The commission of investigation will probe whether the sale was appropriate, if the price paid was appropriate and whether there were any conflicts of interest among Nama's northern advisers.
It will investigate if the actions of the Republic's finance minister Michael Noonan, "including communications with members and officials of the Northern Ireland Executive" and meetings with potential bidders were appropriate.
The commission will also inquire into "anything arising outside the State that it considers relevant".
An interim report to the Taoiseach is expected within three months of the inquiry being set up.
A final report on the first module of its work must be finished by the end of June 2018.
