The Belfast law firm at the centre of a controversy over an alleged £7 million in an offshore account linked to a multi-billion euro Nama deal, has named Ian Coulter, the former managing part of the firm, as the partner who left after the account was discovered.

Mr Coulter is a former chairman of the Confederation of British Industry in Northern Ireland and is a very well-known and highly-respected member of the business community there.

He could not be contacted on Friday.

Independent TD Mick Wallace said in the Dáil on Thursday an audit of Tughans law firm in Belfast had found an Isle of Man account with £7 million in it which was “reportedly earmarked for a Northern Ireland politician or political party.”

He made the comment in the context of remarks about a massive loan portfolio sale last year by Nama, involving property-linked loans with a nominal value of £4.5 billion, and which was sold for a reported £1.5 billion to US private equity firm, Cerberus Capital Management.

The sale was given the name Project Eagle.

In a statement, Tughans solicitors has confirmed it and Mr Coulter worked on Project Eagle, having been engaged by a “major US law firm” that was in turn acting for Cerebrus.

The statement also said: “Following internal investigation Tughans voluntarily brought the circumstances leading to Coulter’s departure to the attention of the Law Society of Northern Ireland.”

The deal was concluded in June of last year. Mr Coulter’s departure from Tughans was announced last January, with no reasons given at the time.

Speaking prior to the latest statement from Tughans, the Cerebrus spokesman said: “We are not and never have been a client of Tughans.”

“We appointed Brown Rudnick as our lawyers. We were advised by them that they would be seeking local counsel support in Northern Ireland by Tughans and that they would be paying Tughans out of their fees.

“Cerberus has never paid Tughans. We want to make it clear that no improper or illegal fees were paid by us or on our behalf and we take any allegation to the contrary extremely seriously.”

Tughans said on Friday it remained constrained by what it can say but the firm’s position is that no part of its professional fee is payable or will be paid to any third party, politician or advisor.

On Thursday night the firm said a former partner had diverted to an account of which he was the sole beneficiary, professional fees due to the firm. The money had since been retrieved, it said.

In a statement on Friday the firm said one of the former advisors to Nama in Northern Ireland, Frank Cushnahan, had offices in the same building as Tughans, and the Nama committee held meetings in the building.

During leaders’ questions on Thursday, Mr Wallace expressed concern about the Nama sale of the Northern Ireland loan portfolio which involved more than 850 properties.

He described it as the “largest ever sale of property in the history of the island of Ireland”.

In a statement on Friday Nama said it appointed Lazard, a major international investment bank, in January 2014 , to advise on and oversee the sales process for Project Eagle, a portfolio which comprised loans with a value of £4.5 billion and which was secured by assets in Northern Ireland, the Republic, Great Britain and other European locations.

“Based on its assessment of the market, Lazard invited nine major global investment groups which had the necessary financial resources to participate and bid in the loan sale process. Cerberus Capital Management emerged as the highest and preferred bidder for the portfolio in April 2014. The sale completed on June 20th, 2014.”

Nama said that prior to confirming Cerberus as its preferred bidder, the agency had sought and received confirmation from Cerberus that no fee was payable by Cerberus to any person connected with Nama in relation to any aspect of the Project Eagle sales process.

“Nama is fully satisfied, having taken advice from Lazard, that the process delivered the best possible return that could have been achieved for Irish taxpayers.”

The North’s deputy first Minister Martin McGuinness called for an immediate and full police investigation into the allegations. In a statement, Mr McGuinness said: “These claims are very serious and must be thoroughly investigated.

“That investigation needs to begin immediately and I would encourage Mick Wallace to speak to An Garda Síochána and the PSNI as a matter of urgency.

“It is absolutely clear that these serious allegations made on the floor of Leinster House need to be subjected to rigorous and full investigation.”

On Thursday, Tánaiste Joan Burton said Mr Wallace should go to the gardaí, to the board of Nama and to the Comptroller and Auditor General if what he described as “disturbing allegations” were true.

The Wexford TD, who has repeatedly called for an inquiry into the operations of Nama, said that following consultation in June 2012 with Minister for Finance Michael Noonan and his then Northern counterpart Sammy Wilson, the agency reappointed Mr Cushnahan and Brian Rowntree to its Northern Ireland advisory committee.

Mr Wallace said that two weeks later, a report from the Northern Ireland auditor’s office into the North’s Housing Executive led to the resignation of both Mr Cushnahan and Mr Rowntree.

The report found guideline breaches in the sale of at least 27 land deals, the executive board being given wrong or no information relating to key property deals, favoured property speculators were allowed to buy land well under market value and interest from other parties not being considered.

Mr Wallace said that despite the report, the two men remained in Nama, one of them until 2014.

Ceann Comhairle Seán Barrett intervened to remind him that it was not practice to name people who were not in the House to defend themselves. He said “this is not an inquisition”.

Mr Wallace also told the Dáil a routine audit of a Belfast-based legal firm Tughans involved in the Project Eagle sale had shown up £7 million in an Isle of Man account, “reportedly earmarked for a Northern Ireland politician or political party”.

Mr Barrett intervened again and said Mr Wallace should give all those details to the Garda Síochána.

The Wexford TD said that in 2009, Ms Burton favoured an oversight committee for Nama and he asked if she would bring the idea forward again.

Ms Burton said she was not familiar with the case he mentioned.

She reiterated that the Comptroller & Auditor General had a very specific role in relation to the oversight of Nama and had produced three reports on the agency, which were “broadly positive”.

She said it was regrettable that Nama ever had to exist but it was very difficult to give a definitive answer on the recovery value of anything which lost its value after the crash. Ms Burton told Mr Wallace: “If what you’re saying is correct, you should go to the gardaí, to the board of Nama and to the C&AG.”