The Office of the First Minister and Deputy First Minister (OFMDFM) sold a former barracks in Belfast for far less than it was worth after it rushed into selling the prime site, a report has said.
Malone Barracks raised £3.8 million but better advice from the Land and Property Service (LPS) may have secured more, the Assembly's Public Accounts Committee added.
MLA Joe Byrne said: "We have serious concerns with the use of an informal unconditional bidding process in the sale of the Malone site.
"We are very clear that sales of land and buildings should be conducted through sealed bids opened in the presence of public sector officials representing the department or public body disposing of the asset. The sale process must be both transparent and well documented."
The committee had particular concerns about the sale of the Malone Barracks. It was disposed of by OFMDFM in December 2003 for £3.8 million following its transfer from the Ministry of Defence. It followed the withdrawal of an earlier higher offer.
The committee said the department could have received far more than the £3.8 million actually realised, had it received better advice from the LPS and had it not rushed into selling this valuable site.
Mr Byrne said: "Perhaps the most unsettling fact was that neither the Department nor LPS were aware that the purchaser of the Malone Road site was acting on behalf of another developer.
"It was only following the Audit Office and committee's investigations that the Department became aware that the site was immediately transferred to a second developer on the day it was sold."
Proceeds from the sale of Malone and Magherafelt Barracks sites, totalling £4.7 million, were to be ring-fenced specifically for projects which would represent a tangible benefit to the peace process. However, proceeds from the sales may not have been used for the intended purpose, the report added.
The report showed that OFMDFM has spent £62 million to date preparing the sites for redevelopment by either private companies or government bodies.