Update 1: A group of hooded protesters have smashed through the door of Sussex House during the anti-privatisation demo, according to eye-witnesses.
Around 30 people now claim to be occupying the building, the on-campus base of university management, which had been closed as a precaution.
Police quickly sought to regain control of the premises, prompting scuffles between students and the authorities.
The protest continues.
Coaches have started arriving at Sussex University for an anti-privatisation demo which is expected to attract many hundreds of students from across the country.
The protest is the latest episode in the ‘Occupy Sussex’ group’s year-long campaign to halt the outsourcing of 10 per cent of the University’s workforce which has attracted the attention of world-renowned academics and celebrities.
The protest is set to start at 1pm. Students from across the UK will march alongside academics and university staff in a mass display of solidarity and anger at the management at Sussex University.
In preparation for the protest, several university shops and bars have been closed.
Support from famous names includes Peter Capaldi, Ken Loach, Noam Chomsky, Michael Rosen and Will Self. The NUS President, Liam Burns, has written an open letter to MPs demanding they sign the EDM in support of the occupation and against university outsourcing.
An email from University Registrar, John Duffy, declared: "The university does not condone this activity, which is against the interests of our students, staff and visitors".
He went on to say that Sussex house, the on-campus base for university management, would be inaccessible between the hours of 1-3pm.
A spokesman for the occupation disputes this claim, saying 'a majority of students on campus both support the campaign and the occupation that is taking place'.
He added: "There are talks of industrial disputes amongst staff, and across campus yellow squares are visible in windows and doors of faculty. The demonstration will bring the campus community together, along with supporters from around the United Kingdom."