The bungled roll-out of a new IT system across the state's public education network could have built up to 20 new schools, the NSW budget estimates committee has heard.

NSW Education Minister Adrian Piccoli​ was forced to defend the $531 million pilot Learning Management and Business Reform (LMBR) system at Parliament House on Monday as the state opposition accused him of implementing the largest waste of taxpayer funding in the Department of Education's history.

Education Minister Adrian Piccoli has been forced to defend Education Department's IT system. Credit:Louie Douvis

The LMBR system has been dogged by complaints and technical faults during its trial in 229 schools.

Last year leaked internal emails revealed that debt collectors had been engaged to threaten schools that failed to pay suppliers of the program which was designed to manage human resources, finance, student information and payrolls.