Students staging a sit-down protest refused to let the vice-chancellor of Sussex University into his office.

Professor Alasdair Smith was forced to answer questions from members of the University of Sussex Students Union (USSU) about the future of 110 students threatened with the withdrawal of library and computing access for non-payment of compulsory tuition fees.

The protest followed an extraordinary meeting of the student body yesterday at which more than 150 people voted to take direct action about the expulsion threat and tuition fees in general.

More than 50 students marched across the Falmer campus before taking part in a sit-down protest outside the main administrative building, Sussex House.

A spokeswoman for USSU said: "A lot of what Prof Smith said we have heard time and time again but we do not think it is enough.

"As vice-chancellor he is a figurehead for the university and should be engaging with the Government to help his students but he has refused to condemn tuition fees or rule out top-up fees in the future."

She added that students had felt forced to resort to the sit-down protest following unsuccessful meetings between USSU representatives and the university.

"The number of mature students at Sussex University has fallen by 17 per cent since the abolition of grants and the number of students dropping out has increased."

Prof Smith said: "The university is sympathetic to the students' case but tuition fees is not ours but Government's policy."

The protest continued today with up to 60 students occupying an office on the ground floor of Sussex House.

Security guards attempted to halt the occupation and police were called.

First year student Robert Lugg, 20, said: "We have been planning this protest for some time and just sprung it on them this morning when we took the building."

Benedict Brook, USSU communications officer, said the occupation was carried out by an independent group of students and was not organised by the union.

The NUS is organising a national university shut down day on Thursday. Students at Sussex will be urged to boycott the university for a day as part of the NUS Reclaim Our Education campaign.