The University and College Union has rejected employers' 0.5 per cent pay offer for 2009-10.
The union's higher education committee voted to reject the offer on 9 October.
Two other unions, Unite and the Educational Institute of Scotland, have also rejected the offer, and as Times Higher Education was going to press the GMB was about to meet to decide its response. A fifth union, Unison, has accepted the increase following a membership ballot.
Michael MacNeil, the UCU's head of education, says in a letter to the Universities and Colleges Employers Association: "Given that three of the nationally recognised trade unions have now rejected the offer, I would urge Ucea to review its mandate and engage in further negotiations."
The offer is fractionally higher than the 0.4 per cent put on the table by Ucea earlier this year, but a long way short of the 8 per cent minimum demanded by the UCU in 2008.
The employers' association said that the union's decision was "disappointing".
A spokesman for Ucea said: "The employers' detailed consultation resulted in a realistic and responsible final pay offer, particularly under the economic circumstances and in the context of recent pay increases."
He added: "We are continuing a dialogue with Unite through Advisory, Conciliation and Arbitration Service-facilitated discussions - a path open to all unions."
Unite, which formally declared a dispute with Ucea over the offer, has been in discussions with the association since August.
Jon Richards, head of higher education for Unison, said he had accepted the 0.5 per cent rise "through gritted teeth".
He said: "The worst effects of the recession are hitting home, and people are worried about keeping their jobs. But they will not put up with this bargain-basement treatment for long and will not rush to pick up such a low settlement again.
"The employers will have to think long and hard about next year's offer, and we are closely monitoring the pay rises of senior management."