Irish parliamentarian Mick Wallace has claimed that a representative of Cerberus told him he would be "sorted" for raising issues relating to the sale of Nama's Northern Ireland loan book.
Mr Wallace told the Dail that he was "summoned" to a meeting by a "public figure" during which the alleged threat was communicated.
The Wexford TD told the Dail the threat was passed onto him by a representative of Cerberus, the US firm that purchased Nama's Project Eagle portfolio of Northern Ireland loans.
Controversy surrounding Project Eagle - which involved the sale of a 850-property portfolio for about £1.2bn - was raised at Leaders Questions yesterday in the Irish parliament.
Cerberus is in the running to purchase a separate property portfolio known as Project Arrow.
The portfolio involves €8.4bn in non-performing loans and is made up of significant residential properties in the republic.
During tense scenes in the Dail, Mr Wallace said the Taoiseach is washing his hands of the controversy.
Mr Wallace claimed a developer whose loans were part of the Project Eagle portfolio, "came to Nama to complain about being approached by fixers who were looking for a backhander in order for him to buy his loans back at 50p in the pound in the autumn of 2013, months before Cerberus even bought it".
He then alleged under parliamentary privilege that he was told by a representative of Cerberus that he would be "sorted" for pursuing the issue.
"Listen, I realise these are serious players," Mr Wallace said.
"And only recently I was actually summoned to a meeting by a public figure and a message was passed on to me from a leading member of Cerberus Ireland that I was going to get sorted.
"Now, why would they have to say that if I'm telling the truth?"
Cerberus has said previously that it did not make any improper payments or pay any illegal fees in relation to the deal.
The company could not provide a response to Mr Wallace's claims in time for going to print.
Mr Wallace hit the headlines in Northern Ireland when he used parliamentary privilege to allege that a Northern Ireland politician had been set to benefit from Nama assets in Northern Ireland.
Today, Stormont's Finance committee is due to discuss the next steps in its ongoing inquiry into the controversial sale of Nama's Northern Ireland assets at Parliament Buildings.