Thousands of lecturers and other academic staff at the UK's leading universities are expected to launch a "sustained campaign" of industrial action in a long-running dispute over pensions.
Members of the University and College Union (UCU) in 67 universities, including Cambridge, Oxford, London School of Economics, Manchester, Liverpool and Leeds, will only work their contracted hours, refuse to cover for colleagues and will not attend meetings.
The union warned that the action could escalate into strikes if the row is not resolved, adding that a million students could be affected. The dispute centres on the universities superannuation scheme (USS), one of the largest private schemes in the UK.
Around 40,000 UCU members are affected, with the union saying changes introduced at the start of the month will see them paying more to work longer, with less protection if they lose their job.
The row is separate from the pensions dispute affecting millions of public sector workers, including 60,000 UCU members, which will lead to a day of action on November 30.
The union said it was keen to resume negotiations, accusing employers of refusing to hold fresh talks.
UCU general secretary Sally Hunt said: "Despite our best efforts to resolve this dispute, we cannot negotiate with an empty chair. Our action will start today and will see thousands of UCU members at universities across the country stop going the extra mile.
"We are keen to resolve this dispute as quickly as possible, with minimal disruption, and hope those universities keen to avoid unnecessary confrontation and disruption will start to apply pressure on those refusing to talk."
A Universities and Colleges Employers Association spokesman said: "Employers are of course extremely disappointed by UCU's plans to take industrial action. The changes to the scheme were approved by the USS trustee board, which includes UCU representation, on June 9.
"This followed exhaustive negotiations and consultation. The changes would be considered moderate by many as they include the retention of a final-salary pension for all existing USS members. Many will be confused by UCU's position."