Union leaders are threatening universities with court action over deductions from staff pay.
The University and College Union (UCU) said Leicester and De Montfort universities acted unlawfully by deducting a full day's pay from staff who took strike action lasting two hours.
They said in the case of De Montfort University it was "particularly galling as vice-chancellor Dominic Shellard was awarded a pay rise of 13 per cent" over the past three years.
Staff at both city universities, Loughborough and others across the country, staged a number of two-hour walk outs in January in a bid to secure a pay increase above 1 per cent.
UCU has written to Professor Shellard and Bob Burgess, vice-chancellor of the University of Leicester, to demand the money is returned.
UCU regional official Sue Davis said: "Hard-working staff took industrial action in a legitimate attempt to reverse years of declining pay.
"To be treated so poorly by your employer leaves an incredibly bitter taste in the mouth.
"At the end of such a protracted, and at times bitter, dispute Leicester's universities have this opportunity to start to improve relations with their staff.
"We consider any money taken an unlawful deduction.
"If the universities do not repay the money, we will seek redress through the courts."
The dispute was resolved at the start of the month when UCU members voted to accept a 2 per cent pay rise.
A spokesman for the University of Leicester, said: "The university made it clear from the outset and notified staff in advance it would withhold a day's pay for partial performance."
A spokeswoman for De Montfort said: "Professor Shellard's basic salary and pension contribution have risen from £249,000 in 2012/13 to £250,000 this year – an increase of about 0.5 per cent. This is entirely within norms for the sector.
"As a member of the Universities and Colleges Employers Association, De Montfort follows national recommendations regarding pay awards as well as deductions in pay resulting from industrial action."