The University and College Union is planning two further days of strike action over pensions in May, targeted to cause "maximum disruption" to examinations.
Last week, in higher education's first national strike since 2006, UCU members at institutions across the UK walked out over employer-driven cuts to benefits in the Universities Superannuation Scheme (affecting pre-1992 universities), government plans to change the Teachers' Pension Scheme (affecting post-1992 universities), plus pay and job security.
Michael MacNeil, the UCU's head of higher education, has outlined plans for further action over the USS.
In a letter to branches dated 25 March, he writes: "I have been asked to consult with pre-92 branches on the proposition that the union should authorise a further two days of strike action during May. It is unfortunate that the employers continue to refuse to talk but, as such, there is no alternative but to target strike action to cause maximum disruption to the administration of examinations."
The union is also "actively considering" action short of a strike, Mr MacNeil says.
In the wake of last week's strike, Sally Hunt, the UCU general secretary, told Times Higher Education: "I thought our members' response was excellent...I was struck by how many members were out on the picket lines."
But a spokesman for the Universities and Colleges Employers Association said the "majority of institutions reported little or no disruption to their students and small numbers on the UCU picket lines".
The employers urged the UCU to "refrain from attempts to seriously damage students" and "to rejoin the formal joint negotiating committee (JNC) process" on the USS, the spokesman added.
Ms Hunt said the UCU's ballot on pensions and the official USS consultation found members were "willing to change, but not to accept the plans on contribution levels, inflation caps (on pension increases for those who are retired or have deferred retirement) and changes to redundancy payments".
Last July, after two years of talks on the USS failed to produce a deal, the independent chair of the JNC, Sir Andrew Cubie, used his casting vote to back the employers' plans.
The changes were modified after a consultation with USS members. But the UCU is blocking their implementation - originally scheduled for 1 April this year - by refusing to attend the JNC, which cannot be quorate without it.
UCU representatives said that if they attended, the chair would simply use his casting vote to back the employers without negotiation.
Ms Hunt said: "If we can negotiate a solution...both sides will have to find a compromise. Using the casting vote to impose their view, that is not a negotiation."
Employers said the union agreed the process for scheme change and the appointment of Sir Andrew.