There has been a call to investigate the sale of a NAMA portfolio after it emerged it was sold without being put on the open market.

The State agency sold Project Tolka for €455m in a targeted marketing process that resulted in three bidders for the loans after a selection process.

The information emerged in a Dáil reply to Fianna Fáil's finance spokesman Michael McGrath from Minister for Finance Michael Noonan.

The reply shows the developers, whose loans were sold, also identified potential bidders who were included in a panel of potential buyers.

Mr McGrath called for the deal to be examined by the Comptroller and Auditor General and said it could not be described as "fully open and competitive".

The reply shows 16 potential acquirers were initially considered.

Three bidders were selected because they met the minimum reserve price for the portfolio.

Minister Noonan said NAMA was advised that the shortlist of bidders was sufficient to ensure a competitive process. 

He said there was a high degree of competitive tension generated throughout the sales process.

NAMA was advised on the sale by Eastdil Secured.

The portfolio comprised of loans from developers John Flynn, Paddy Kelly and the Dublin-based McCormack family.

Among its assets was the Burlington Plaza office complex on Burlington Road and the Clarion Hotel in Liffey Valley.

It was sold at a discount of up to 70%.

The portfolio was bought by US group Colony Capital.

Mr McGrath said: "While it is possible that NAMA received the best possible price for the loans concerned, the sales process could not be described as fully open and competitive".

He added: "It is difficult to understand the reason why such a selective approach was taken by NAMA in relation to potential bidders.

"A peculiar aspect of this sales process is that debtors and NAMA agreed on the list of credible potential bidders.

"I think there needs to be an explanation as to why the debtors had an involvement in the selection of potential bidders," he said.

In the Dáil reply, Mr Noonan said NAMA's function was to get "the best achievable financial return for the State."

He said full co-operation of the debtors was key to achieving the maximum value of the portfolio.