Update 10am: The Comptroller and Auditor General has said Nama did not take sufficient action when concerns were raised about the sale of its Northern loan book.
Seamus McCarthy said he has also not had sufficient assurance that a different strategy from Nama in the sale of Project Eagle would not have resulted in greater value for the taxpayer.
He is being quizzed by the Public Accounts Committee after issuing a report saying the taxpayer may have lost as much as €230m on the sale.
Mr McCarthy said he believed Nama did not deal properly with a possible conflict of interest when its advisor Frank Cushnahan said he was also advising debtors.
"Nama sought and relied on an assurance from Cerberus that no fee or payment was payable to anyone connected with Nama.
"My view is the allegations of Mr Cushnahan's involvement in a fee-sharing arrangement warranted more action by Nama when the issue came to light," he said.
Frank Cushnahan has denied any wrongdoing, saying he did not make a penny from the €1.6bn sale of the Project Eagle portfolio.
TDs will question senior figures from Nama about the sale of its Northern Ireland loans today.
Chairman Frank Daly and chief executive Brendan McDonagh will both appear before the Public Accounts Committee, which begins its hearing into Project Eagle today.
The PAC will also hear from the Comptroller and Auditor General about his report, which found the taxpayer missed out on around €230m on the €1.6bn sale - something Nama rejects.
Committee chairman Sean Fleming said: "We will be examining the issue of the Project Eagle loan sale process, the price and the value for money."
He said the PAC examination of the issues surrounding the sale will run for a number of weeks.