NAMA bosses admit they have no power to stop former staff bidding for properties controlled by the agency.
Its chief executive Brendan McDonagh admitted that companies employing former NAMA staff have bid for some properties.
A number of former staff have joined private equity companies that later bid for NAMA assets, he confirmed.
But he insisted the issue of "insider knowledge is completely overblown".
Mr McDonagh was responding after members of the Dail Public Accounts Committee (PAC) raised fears in relation to "high staff turnover" at NAMA.
He appeared in front of PAC to deny a series of serious allegations made to gardai by one of his agency's former portfolio managers.
NAMA was the victim of "a carefully orchestrated operation targeted at a small number of media outlets and Oireachtas members", Mr McDonagh told the committee.
Sixty-two officials have left NAMA since the agency was set up in 2009 -- 29 of those since the start of this year, the committee was told.
"We are aware of a number of people who have left us and joined firms that bid for NAMA assets," Mr McDonagh said.
But that was not a problem because assets were correctly marketed, usually through outside property agents, he said.
Mr McDonagh denied allegations made in recent days that sensitive information relating to developer Paddy McKillen was leaked to third parties from NAMA.
That would also include information about credit decisions taken when the loans were made, he said.
Mr McDonagh and NAMA chairman Frank Daly rejected allegations, made to gardai by former portfolio manager Enda Farrell, that NAMA loans were deliberately undervalued by the agency.
Mr Daly said questions should be asked about Mr Farrell's motivation in making the allegations.
Mr Farrell is one of two former executives being investigated by gardai following complaints from NAMA.
The Garda Bureau of Fraud Investigation has submitted a file to the DPP recommending that Mr Farrell be charged with leaking sensitive commercial data to outside companies.
Earlier this week, the Irish Independent revealed Mr Farrell's allegation that he had passed confidential information to a third party, specifically highly sensitive material relating to Mr McKillen's private and business affairs.
Mr Farrell handed a dossier to gardai containing emails and other correspondence which, he claims, proves leaking was rife within the secretive agency.
He also alleges he was encouraged to deliberately undervalue property loans.
A file on the matter that is i n circulation among politicians and some of the media has not been seen by him, or his agency, so it can't be sure what else is contained it in, Mr Daly said.
"Its intended purpose is clear -- to damage NAMA and thereby undermine the financial institutions of the State," Mr McDonagh said.
"Presumably, if enough mud is thrown, some of it will stick," he added.
Mr McDonagh and Mr Daly had asked to appear at the PAC in order to address the allegations. They rejected allegations that loans were deliberately undervalued by the agency.
"In relation to allegations of which it has become aware, NAMA is satisfied that they are unfounded," said Mr McDonagh.
NAMA chiefs denied suggestions that the NAMA valuation process resulted in systematic undervaluation of loans, saying it has suffered a €3.6bn impairment on its loans.
"You could say we paid too much," Mr McDonagh said.