Lecturers are "solidly" supporting a 48-hour strike over pay as picket lines were mounted outside universities across the UK.

Members of the University and College Union (UCU) are also refusing to work overtime, set additional work, or undertake any voluntary duties like covering timetabled classes for absent colleagues.

General secretary Sally Hunt said: "We are getting reports of really solid support from picket lines across the UK.

Glasgow School of Art Staff and members of the UCU (University College Union) strike outside the Art School buildings, Renfrew Street, Glasgow. Video by Kirsty Anderson. 

"It is a disgrace that the employers' intransigence over pay and conditions for university staff has forced us out on strike. The time has come to reverse the holding down of salaries that has seen staff pay fall by 14.5% in real terms since 2009. We hope universities will now come back to us with a decent offer and we can avoid further disruption."

If the dispute is not resolved in the coming weeks, members have agreed to further strike action which could affect open days, graduation ceremonies and the clearing process.

The union is also beginning preparations for a boycott of the setting and marking of students' work to begin in the autumn.

The union has rejected a 1.1% pay offer from employers, arguing that universities could afford to pay more after the pay and benefits of university leaders went up by 5.1% last year.

Protests are being held around the UK with rallies in Belfast, Birmingham, Brighton, Cambridge, Glasgow, Leeds, Liverpool, London, Manchester, Newcastle and Sheffield.

A university employers' spokesman said: "Our HE institutions tell us that they anticipate minor impact and minimal student disruption from UCU's planned strike days this week. They know that the vast majority of their staff understand the current funding environment and can see that the final offer, with substantial extra for the lower paid, endeavours to be fair without putting additional jobs at risk.

"Higher education institutions overwhelmingly tell us they are anticipating no to low impacts on both days. Even for examinations, which are still taking place at some institutions, more than nine out of 10 report that a no to low impact is anticipated.

"This industrial action is naturally disappointing given the very good pay offer, plus the joint work on gender pay and casual employment that is on the table. We would like to see UCU consulting its members on the final offer rather than seeking to take action that could damage institutions and harm their students.

"However, it is important to note than less than 5% of academic staff have voted to support this planned strike action. The student experience is a primary concern for all institutions and so staff will be doing their very best to protect students."

Unite, which has around 12,000 members in the higher education sector, said it was consulting on the possibility of joining the action. A ballot closes on June 6.

National officer Mike McCartney said: "We are calling on Unite members to reject the offer on the table. They have seen their pay slashed over recent years, while many university bosses are raking in more than the Prime Minister.

"Clearly there is unfairness in the pay system and that hurts our members who are mainly technicians, porters and cleaning staff without whom universities would not function. These are the workers who are the key to providing a good student experience."