As Peter Robinson prepares for questions in the Assembly over his role in the controversial £1.2bn Nama deal, details have emerged of a meeting between the First Minister and an unsuccessful bidder for the property portfolio in 2013.
Information about the meeting emerged in correspondence from US firm Pimco to the Assembly's Finance Committee.
Committee chair, Sinn Fein's Daithi McKay, conducting the Nama inquiry, described the details of the meeting as "a very significant development".
Mr Robinson was accompanied at the meeting with unsuccessful Nama bidder Pimco by then-Finance Minister, Sammy Wilson; then-Nama advisor Frank Cushnahan, and former Tughans solicitor Ian Coulter.
The MLA said Pimco "mistakenly believed" the meeting was "taking place under the auspices of the Executive".
In the correspondence, Pimco says it was approached by New York law firm Brown Rudnick and introduced by them to two other unnamed parties. Pimco says it was advised by these parties that "the Northern Ireland government was concerned to ensure that there would not be a fire sale of homes and businesses".
Pimco was also told that the NI Executive wanted to meet them to assess their suitability.
"It is our understanding Pimco was not the only firm invited to meet with the representatives of the Northern Ireland Executive at that time," the firm said.
Mr McKay said: "This letter raises further questions about the Nama sale.
"I will be asking why no record of this meeting has been made available to date by the Department of Finance."
Mr Robinson is to appear before the Finance Committee this morning as part of its inquiry into the Nama deal, which has involved claims that millions of pounds were to be paid in 'fixers' fees' to individuals.