The move comes just weeks after he raised concerns in the Dáil on the sale of the Project Eagle loans.
Mr Wallace more recently claimed that a Nama official asked and received a €15,000 bribe — an allegation which led to the TD making a statement to gardaí about the matter last Friday.
Nama has strenuously denied the claims and its CEO, Brendan McDonagh, asked the Garda Commissioner to investigate the allegations.
Yesterday, Mr Wallace issued a statement in which he said it was now time for a “forensic examination” of Nama, “now rather than later” that would preferably be led by experts from outside the State so as to ascertain “whether the maximum return has been achieved for the Irish taxpayer in all transactions to date”.
“We also need to consider how Nama should best deal with its remaining loan portfolios and assets,” he said.
Specifically, he said the proposed sale by Nama of Project Arrow — which contains 500 loans — should be suspended.
Referring to the Project Eagle controversy, he said: “Many may feel that the horse has bolted but that’s not completely true. Presently, Nama is looking to sell Project Arrow — which has a par value of €8.4bn — in one lot.
“This is made up of 90% Irish real estate, of which 50% is residential and the rest of mixed use. The loans are generally non-performing, so we are likely looking at a very serious write-down.
“Once again, Nama are creating a scenario whereby only a US vulture fund is likely to have the wherewithal to purchase, thus excluding Ireland-based investors.
“Also given that 90% of Project Arrow is Irish real estate, we are most likely to see many medium-sized Irish businesses driven to the wall as the new owners ruthlessly chase down the loans. The winner from this exercise will not be the Irish taxpayer or the relevant Irish businesses but faceless US vulture funds.”
Speaking on Newstalk, Mr Wallace said allowing the sale to go ahead would be “a mistake” as some assets previously sold by Nama had been re-sold within a relatively short time frame for a sizable profit.
“I think that we’re selling too many of these assets below the real value,” he said. “The more stuff you put in the bag, the bigger you make the portfolio the less you’re going to get per item, that’s a given.”