Some of the nation's biggest private training colleges have been revealed to graduate disturbingly few students while receiving hundreds of millions of dollars in government subsidies.

Only one in 10 students who enrolled in government-supported courses at one leading provider received a diploma within two years, according to new figures from the Department of Education and Training.

Education Minister Simon Birmingham. Credit:Alex Ellinghausen

The figures show just 300 of the 2762 students who enrolled in Careers Australia courses in 2012 had completed their studies by 2014.

Careers Australia, which has 15 campuses across Australia, was accused earlier this year of employing door-to-door salespeople who targeted potential students in disadvantaged areas with free laptops. The college's salespeople were also accused of enrolling poor students with fake entrance exams.