The DUP has claimed information released by the Republic's Department of Finance contradicts Martin McGuinness's claim that he was "kept in the dark" about the deal for Nama's northern loan portfolio.
Michael Noonan's department released a tranche of documents relating to the bad bank's sale of its Northern Ireland debts on the eve of the latest sitting of the Dáil's Public Accounts Committee.
The DUP yesterday seized on minutes of a conference call from January 2014 that was arranged to discuss 'Project Eagle'.
The call involved Mr Noonan, Mr McGuinness and Peter Robinson, as well as Department of Finance official Declan Reid and Nama's Ronnie Hannah.
The call was mentioned in Mr McGuinness's evidence last week to Stormont's finance committee.
According to Nama's record, Mr Noonan, Mr Robinson and Mr McGuinness discussed Nama's decision to sell its loan book by auction, rather than accepting an unsolicited offer from US investment fund Pimco.
The minutes make reference to a letter of intent from Pimco regarding its management of assets in the event of a successful bid.
Mr Robinson is quoted as saying that "they (thought to mean the Stormont executive) did not align themselves with any particular buyer".
But the minutes note: "However, he (Mr Robinson) reiterated the comfort provided by the commitments Pimco had made to the executive through a letter of intent regarding their management of assets if they were the successful acquirer."
The first minister agrees to provide Nama with the letter of intent "for informational purposes".
The minutes do not record any input into the conversation from Mr McGuinness and while the deputy first minister acknowledges that he was involved in the call, he insists that he was not privy to other crucial meetings relating to the Nama deal, including a meeting with former US vice president and Cerberus chairman Dan Quayle in March 2014. New York firm Cerberus were ultimately the successful bidder.
Former finance minister Simon Hamilton, who has yet to say when he is available to give evidence to the Stormont Nama inquiry, claimed the conference call minutes blew a "massive hole in the credibility of the deputy first minister’s evidence".
"The significant aspect is not that he was present for the call but that what was discussed during the call has previously been denied by Mr McGuinness," Mr Hamilton said.
"Mr McGuinness has denied being briefed on these matters or that he was aware of the MoU (memorandum of understanding) from Pimco – the evidence from Michael Noonan’s department flatly contradicts that and shows that far from the deputy first minister being kept in the dark was intimately involved in the discussions."
The Irish News asked to speak to the Sinn Féin deputy first minister but he was unavailable.
However, Máirtín Ó Muilleoir, one of the party's representatives on the finance committee, said there was a "paper trail" that demonstrated how Mr McGuinness was excluded from key meetings.
"I welcome Simon Hamilton breaking his silence on the issue of the sale of Nama's northern loan portfolio – hopefully this signals a willingness to help shed light on an important issue of public interest," the South Belfast MLA said.
Mr Ó Muilleoir said Mr Hamilton, whose former department has faced criticism for not releasing information pertinent to the Stormont inquiry, should agree to appear before the committee.
