Sinn Fein has failed to respond to questions about decisions by Martin McGuinness to approve controversial 'public private partnership' schemes to build new schools.
Figures published by The Irish News this week revealed the true cost of PFI and PPP projects signed off by education ministers.
Over a decade, 20 schools received new buildings through PFI/PPP - the initial capital cost was a combined 374 million.
However, the estimated total repayment, when interest is taken into account, will be greater than 1.5bn.
Many were given the green light by Martin McGuinness during his period as education minister. The rest were approved by direct rule ministers.
At the time, Mr McGuinness said such schemes offered "real potential for value for money solutions" to pressing capital investment needs.
More recently, Sinn Fin has expressed the view that PFI (private finance initiative) represents poor value for the public sector.
Under such schemes, private companies design, build and help run new schools in return for an annual fee from government and income from the property outside school hours.
The mortgage-style nature of the various deals means the money will not be paid back entirely for another 25 years.
In one instance, a project will end up costing almost seven times more than the initial capital price of the building scheme.
The Department of Education has now effectively abandoned PFI/PPP, admitting that it does not offer the best value for money.
In 2000, Mr McGuiness gave the go-ahead for St Genevieve's High School in west Belfast to receive a new build.
The initial cost was 11.5m but the total repayment, covering capital, maintenance, services and interest will total 73.6m.
At the school's official opening, Mr McGuinness spoke about the "reality of what can be achieved through private/public partnership".
His capital announcement of March 2001 also included approval for a PPP scheme in Derry diocese involving separate 22.5m builds for St Cecilia's and St Mary's Colleges.
When the final repayment is made in 2035, 184.6m will have been paid back.
A year later, he announced that 54m would be ploughed into schools "in desperate need" with an additional 53m of PPP money to help even more schools.
This included the De La Salle PPP Project, which involved builds for four schools including St Mary's PS in Portglenone and St Patrick's Grammar in Downpatrick.
While Mr McGuinness made the announcement, the contracts were not completed for another three years under direct rule.
At that time, Mr McGuinness said he shared union concerns about the use of PPP, but insisted the backlog of major school works could not be met by conventional grants alone.
There was no response from Sinn Fin yesterday.
