A marking boycott by lecturers at 69 universities will get underway today, amid a dispute over bosses' plans to slash their pension fund.

More than a million students will be affected as members of academics' union UCU down biros in a bid to stop cuts by Universities UK (UUK) that could see staff lose up to £12,000 a year in retirement.

Academics will stop marking work, returning marks and setting exams and coursework for the first time since 2006.

And the prospect of a historic full academic boycott was raised by the union yesterday in response to threats by hardline bosses who dock 100 per cent of striking workers' pay.

Head of bargaining Michael MacNeil warned vice-chancellors they will "exacerbate and prolong what is already a bitter dispute."

York University has already declared it will dock all pay from day one of the strike while other institutions are considering similar action.

But UCU general secretary Sally Hunt said: "Punitive pay docking could lead to lectures and seminars being cancelled as members refuse to work for free.

"Any institution docking full pay and claiming it has students' interests at heart is lying."

Ms Hunt set out her union's plans to "isolate the worst offenders as pariahs" as part of a full boycott by academics across the world.

Today's boycott was boosted by news that Imperial College London leaders spoke out against the pension cuts in a message to staff.

Oxford, Cambridge and Warwick are among other institutions who have criticised UUK's unnecessarily pessimistic assumptions about its pension fund.