The Northern Ireland Assembly's Finance Committee is examining the claims, made in the Dáil (Irish Parliament) by independent member Mick Wallace.
He claimed £7m in an Isle of Man bank account had been "reportedly earmarked" for a Northern Ireland politician.
Firms involved in the transaction have denied any wrongdoing.
The chair of the finance committee, Sinn Féin's Daithí McKay, announced on Friday that he would convene an emergency sitting to examine Mr Wallace's allegations.
The sale, completed in April 2014, was the biggest ever property deal in Northern Ireland.
The Republic of Ireland's state-controlled National Asset Management Agency (Nama) sold its entire 850-property loan portfolio in Northern Ireland to the New York investment firm Cerberus for more than £1bn.
No witnesses are expected to appear before the Finance Committee, and only assembly members will attend.
The meeting began at 10:00 BST on Tuesday and after a short closed session, public proceedings recommenced at about 10.35 BST.
Allegations that a politician stood to benefit from the sale of Nama's Northern Ireland property loan holdings are being discussed by Stormont MLAs.