Some professors at Northampton University have had their pay frozen after a formal evaluation found that they were not meeting expectations for their roles.
Ann Tate, Northampton vice-chancellor, prompted protests in the summer when she proposed a new pay scale for professors, between £40,335 and £46,758, putting them in the same pay band as readers and principal lecturers at the university.
Some 19 professors wrote to Ms Tate to complain that the move would "rapidly have a negative effect on the university's ability to achieve the goals for research and knowledge transfer which it has set".
In 2005, when the institution was applying to become a university, Northampton had established professorial salaries on a scale between £43,721 and £52,105 for the 2006-07 academic year. "It seems extraordinary that two years later the university is reverting to its position prior to 2005," the professors said.
The letter's authors said one of their number was told she had not been classed as "a leading authority in their subject with widespread professional or public recognition", when this was a key criterion for her job.
The university decided in September, after the complaint, to move 60 per cent of the professors - who number about 25 - to a higher pay grade. But it left the rest on grade 9 on the grounds that they had fewer managerial responsibilities.
A university spokesperson said Northampton used the "higher education role analysis toolkit" to carry out job evaluation, which ensured all roles "were evaluated fairly, transparently and consistently" to ensure "equal pay for work of equal value" for all staff.
Sue Davis, regional officer for the University and College Union, said the union was unconvinced by the process. It had raised the issue with the vice-chancellor.