A top law firm had €9.8m in a bank account "reportedly earmarked for a politician" after a major property deal, it was claimed.
The sensational allegation was made in the Dáil by Independent TD Mick Wallace against the Belfast law firm Tughans. Mr Wallace raised concerns over the sale of Nama's Northern Ireland property portfolio in April 2014.
Tughans has denied Mr Wallace's allegations.
In a statement last night, the company said a former partner did divert money into a bank account, adding that the partner had since left the firm.
Tughans said: "We can confirm that a former partner diverted to an account of which he was the sole beneficiary professional fees due to the firm without the knowledge of the partners. We have since retrieved the money and he has left the practice. The practice is not linked to any political party nor has it ever made party political donations."
Mr Wallace earlier named Tughans as having acted for Cerberus, which bought the Nama portfolio in Northern Ireland, and that "a routine audit showed that £7m (€9.8m) ended up in an Isle of Man bank account".
"It was reportedly earmarked for a Northern Ireland politician," he added. Mr Wallace was urged by the Ceann Comhairle Sean Barrett not to "make cases against people who are not here to defend themselves".
Mr Wallace continued: "We are talking about billions of taxpayers' money," and insisted: "I am not telling anything that was made up."
Addressing Tánaiste Joan Burton, Mr Wallace asked if she had no concerns about "a routine audit of a solicitor's firm that looked after the deal where €4.5bn of assets were sold for €1.5bn, with a massive loss for the Irish taxpayer? The routine audit showed that £7m sterling ended up in an Isle of Man bank account".
The Tánaiste said the Comptroller and Auditor General had oversight of Nama.
In a statement, Nama said it was "fully satisfied" that the sales process for the Northern Ireland loan portfolio "delivered the best possible return".
It added that the Lazard investment bank advised on and oversaw the sales process.
Based on its assessment of the market, Lazard invited "nine major global investment groups" to participate in the process. Nama said that Cerberus emerged as the highest bidder following a competitive sales process.