NSW Teachers Federation Dubbo organiser Duncan McDonald said the figure was unsurprising.

Taxpayers forked out $73,200 per graduate from private colleges on average, but only $10,500 per graduate in TAFE courses in 2014.

The analysis was done by the NSW Greens based on the federal Department of Education and Training’s funding figures and the number of vocational graduates in 2014.

The cost blowout is in part because despite deep funding cuts, TAFE maintained significantly higher completion rates than private colleges in 2014 (87 per cent compared with 44 per cent for private providers).

“It’s not a surprise and that’s because what we see is a shoddy private providers taking advantage of poor government policies,” Mr McDonald said.

“And they’re making huge profits at the expense of the taxpayer.”

It was a drain on the public purse, Mr McDonald said.

“Because it’s so unregulated, that’s where the problem begins to really take on this magnitude. It’s really government policy that’s the problem,” he said.

The NSW government has cut funding to TAFE, saying it is less cost-efficient at delivering skills training than the private sector, particularly industry bodies. Since 2012, some 4600 TAFE teachers and staff have been sacked and enrolment numbers have dropped by 80,000.

Student enrolments at TAFE Western Institute dropped by about 4000 or 20 per cent from first semester of 2014 to the first half of 2015, following the introduction of the NSW government’s controversial Smart and Skilled reforms to vocational education.

NSW Greens MP David Shoebridge said the privatisation of vocational training “has been a comprehensive failure” that both major parties shared responsibility for.

“In a tight fiscal environment it is criminal to see billions of tax dollars being squandered to prop up private providers who aren’t even giving their students a qualification.

“The whole system needs to be scrapped and all government funding for vocational education and training returned to the public sector.”