Up to 65,000 university students - 30 per cent of graduates - will be jobless four months after finishing their studies, and those finding employment will be earning less, the federal government has forecast.

The predicted major downturn in graduate employment will occur at the same time student debts are expected to soar with the deregulation of university fees and an increased interest rate applied to student loans.

Preliminary estimates also indicate that the amount of student debt owed to the government, which will never be repaid, could jump to $3 billion a year under the new rules.