Students bussed in to join University of Sussex protest
Students from around the UK have joined a University of Sussex protest over the outsourcing of support services.
The university stepped up security on the Falmer Campus amid claims hundreds more demonstrators would support the six-week student sit-in.
Sussex Police said protesters had started to cause "significant damage" to Sussex House in an effort to gain entry, before breaking in.
No arrests have been made, the spokesman said.
Scores of students were bussed in from other universities to join their local counterparts.
Supt Grenville Wilson said: "The protest initially started out as peaceful and police were able to support the university security with neighbourhood policing officers and police liaison officers.
"When officers arrived at Sussex House there was some resistance to their presence and some coins were thrown," he said.
"A large number of people were pushing towards the doors of Sussex House.
"At this point force could have been used, such as batons, by the officers but a decision was made for officers to step back from the situation for the safety of the protesters, university staff and the officers themselves."
He said the protesters then moved on to Bramber House, where a sit-in began more than six weeks ago.
"The protest became peaceful again and officers were able to hand the security of the campus back to the university security team," he said.
"No arrests were made during the protest, however, a full investigation has now commenced to identify those responsible for any offences that were committed."
The occupation began in a conference room in Bramber House on 7 February following a 300-strong staff and student protest.
Since the start of the sit-in over proposals to outsource 235 campus jobs, the students have said their action has gone from "strength to strength".
University officials have granted open access to the building between 08:00 and 22:00 GMT, while a number of high profile speakers and notable academics have given talks at "open lectures".
A spokesman for the protesters said: "The way we started off was about encouraging people to use the space.
"At present, the campaign has such a high profile it is used as a space for dialogue, work and engagement.
"People want to see what we are doing, rather than us seeing what others are doing.
"We've got academics bringing their classes up - the campaign is growing day by day."
John Duffy, registrar and secretary of the University of Sussex, said: "The violence at Sussex House and the attempt to disrupt the normal running of our campus is shocking and appalling.
"We condemn the damage caused.
"We cannot tolerate today's violent behaviour, for which there is no excuse. This sort of behaviour threatens the good order and running of the campus for our students and staff.
"We thank the police and our security teams for keeping staff, students and visitors safe.
"We're working with the police to assess the impact of the damage which has been caused in particular areas of the campus."
The university has said the transfer of some services to an external provider was an "ongoing process", and talks with unions and the staff involved were continuing.