Members of the University and College Union (UCU) have criticised the management of the University of Manchester over proposed redundancies.
The university has over 40,000 students
The union said that the 400 job cuts would intensify the workload for those who remained and asked for a moratorium on current job recruitment.
The university is £30m in debt but said there will be no compulsory job losses.
Members of the union and university management are due to meet again on Wednesday to discuss the situation.
Richy Carrothers, regional organiser for the UCU, said that the union would like to see the university's accounts to better gauge where the overspending had happened.
He stressed the need for the institution to bring its current spending under control by holding back on staff recruitment and the voluntary severance package offered was poor.
The UCU represents over 4,500 people at the university.
In 2004, the university merged with the neighbouring Institute of Science and Technology to create one of Europe's biggest universities.
University president Alan Gilbert said that one of the main problems was the number of staff taken on since the merger, swelling the workforce by a total of 2,800 people.
The university now has 40,000 students and says it aims to become one of the best in the world by 2015.