The University and College Union sent freedom of information requests to 158 higher education institutions, which revealed that in most cases vice chancellors were able to able to attend remuneration committee meetings, where their salaries are decided.
Of the 142 institutions that responded to questions about remuneration committee membership, 47% said that vice chancellors were members of their committee.
Additionally, of those universities whose vice chancellors were not members of a remuneration committee, only seven said that their vice chancellors did not attend remuneration meetings.
UCU general secretary Sally Hunt said: “It is quite staggering that just seven universities say their vice-chancellor was neither a member of the committee that sets their pay, nor allowed to attend the meetings.
“For too long universities have got away with painting remuneration committees as independent bodies to deflect attention over senior pay.”
In a test of transparency, the FOI issued by the UCU also asked for a copy of the most recent committee minutes, to which only a quarter responded with unredacted copies.
Hunt added: “The time has come for proper transparency of senior pay and perks in our universities and that starts with full disclosure of the shadowy remuneration committee.
“It is scandalous that three-quarters of universities refuse to issue full minutes of these meetings.”
According to a Times Higher Education pay survey, the average pay for vice-chancellors has more than doubled from £165,105 in 2005/6 to £257,904 in 2015/16.
The Office for Students, which will begin operating on 1 April, has said it will tackle the issue of pay for senior university staff, but Hunt remained sceptical, suggesting that previous attempts to address the problem have failed.
The Committee of University Chairs is currently holding a consultation on a draft remuneration code for the higher education which is due to conclude on 12 March 2018.
A Universities UK spokesperson said the consultation on a new code would provide “important guidance for university remuneration committees to ensure senior pay decisions are fair, accountable and justified whilst recognising that competitive pay is necessary to attract first rate leaders”.
A Department for Education spokesperson acknowledged the problem.
“It should not be the case that vice chancellors sit on the remuneration committees that set their salary, nor should we be seeing unjustified and excessive pay rises,” they said.
“The draft remuneration code from the committee of university chairs, which is currently out for consultation, reiterates the importance of independent and transparent remuneration committees.”