A union is threatening to take legal action against any university which docks its members a day's pay for taking part in upcoming strike action.

Members of the University and College Union (UCU) are to begin a series of two-hour walkouts on Thursday 23 January.

The union claims a number of universities have sent letters to staff saying they will deduct a day's wages from anyone involved in the action.

University employers said they had taken legal advice and that institutions were entitled to cut pay by this amount for those taking part.

The University and Colleges Employers Association (UCEA) has expressed disappointment at what it described as the UCU's “latest tactic to disrupt higher education institutions”.

The two-hour walkouts are an escalation of UCU's industrial action over a 1% pay rise offered to university staff, and come after its members, along with those from a number of other unions, took part in two one-day walkouts in the autumn term.

UCU says the pay offer means its members have faced a 13% pay cut in real terms since October 2008.

The latest action could see students across the UK face major disruption. Tens of thousands of lectures, seminars, tutorials and practicals will be at risk of cancellation when the walkouts start, the union has claimed.

It has also warned that if there is no breakthrough in the dispute, its members would consider a boycott of exam marking, which could potentially mean students are left without the final marks they need to gain their degree.

The first two-hour strike will take place on Thursday between 11am and 1pm, followed by further strikes on Tuesday January 28 between 2pm and 4pm and Monday February 10 from 9am to 11am.

UCU general secretary Sally Hunt said: “Any university that tries to dock a full day's pay for a two-hour walkout will face a legal challenge from us and an lecturer escalation of strike action, as well as risking considerable damage to their reputation for fair play.

“Perversely, any universities that do dock a full day's pay will ensure far greater disruption for their students, which suggests the approach has nothing to do with the welfare of staff or students and is based around penny-pinching and bullying.”

A UCEA spokesman said a significant number of universities are withholding a full day's pay from union members taking part in the strike action and all are withholding pay for a minimum of two hours.

“The higher education unions are fully aware of the employers' consistent position regarding withholding pay for partial performance, and that they are entitled to withhold a full day's pay if staff do not work normally,” he said.

“UCU's declaration to escalate action right at the outset is clearly intended to try to deter employers from doing this, as they had hoped that the two-hours strikes would bring maximum disruption to student education with minimal impact on members' pockets. It is disingenuous for UCU to suggest that the employer should be blamed for any further disruption they may call on their members to cause.

“Higher education (HE) institutions do not accept partial performance and many will be deducting a full day's pay in order to limit the impact on their students. Institutions that have decided on this occasion to withhold two hours' pay and to pay striking staff for the rest of the day reserve the right to withhold full pay if the action continues. HE institutions are dismayed that this form of industrial action has been designed to damage students' education but will do their very best to protect their students.”