Hundreds of staff at the University of New South Wales are facing the sack under a proposal from management to save $51 million a year by cutting back on its student and corporate support services, finance, IT, media and marketing operations.

A leaked "operational excellence" proposal obtained by Fairfax Media shows $29.9 million has been budgeted for redundancies through severance pay across the departments.

The National Tertiary Education Union estimates that up to 415 full-time jobs could go under the two-year plan.

"The actual number of professional staff who could be affected is much higher, when taking into account that many professional staff members work on a fractional basis," the union said in a statement.