Students have occupied part of a university building in opposition to plans to outsource catering and estate management services

Around 40-60 students have occupied a conference centre and top floor of a University of Sussex building as "a last recourse" to prevent the privatisation of campus services.

The occupation follows a demonstration on Thursday when 300 staff and students marched through campus to oppose the outsourcing of catering and estate management services at Sussex.

At the end of the protest, a group of 40 students occupied part of Bramber House, where an external event was taking place.

A further 20 students joined the occupation over night, according to a Sussex Against Privatisation spokesperson, despite the presence of university and private security staff.

The university provoked anger when it announced in May that it was to sell off some campus services, meaning 235 workers will be transferred to private companies from August 2013.

Since then it has held meetings with trade unions, staff and students but pressed ahead with the bidding process to find a private partner. Sussex Against Privatisation says the opposition to outsourcing services is strong and that its actions are a "last recourse... in order to ensure that student and staff voices are heard".

"We had a large rally yesterday and a solidarity demo this afternoon. But these events aren't just a one-off, there've been boycotts and petitions held throughout the year in opposition to the university's plans.

"While privatisation will have an impact on students' lives in terms of the quality of services, our first concern is the impact this will have on staff – it's their job security that will be put at risk."

John Duffy, University of Sussex registrar, says there will be no redundancies as part of the outsourcing, and that staff's terms and conditions will remain the same.

"This is a long-term strategic development by the university to ensure that we can enhance and develop the high-quality services we provide to our students and staff as we grow, with student numbers increasing from fewer than 11,000 in 2008 to a projected 18,000 by 2018."

"As we go through the [bidding] process, we are providing information and support to those staff who will be transferring to external partners. We also continue to meet and discuss our plans with the three campus trade unions. We are keeping other staff and students informed about the process."

But Caroline Lucas, MP for Brighton Pavilion, says the university has failed to consult staff and students.

"It is deeply concerning that the decision to outsource university services has been made with so little transparency or consultation– making it impossible to know whether these plans are either sustainable or good value for money.

"I've raised these fears with the management and am still waiting for an answer as to why it refused to consider any in-house service improvement plan, instead presenting 'doing nothing' as the only alternative to outsourcing.

"The university now has a duty to listen to the concerns of staff, many of whom feel anxious about their futures, trade union representatives and students who are today challenging the privatisation agenda in education."

Sally Hunt, general secretary of the University and College Union, has expressed her support for the occupation: "The university administration is attempting to unilaterally drive through a deeply unpopular and flawed reform, without proper consultation or assessment of alternative solutions.

"We stand with our members in their struggle to safeguard the working conditions of staff at Sussex and to uphold the idea of a public university."