Animal rights campaigners have vowed to continue their campaign against Oxford University's plans to build a laboratory for animal experiments.

The calls followed a demonstration by about 50 people in the centre of Oxford on Saturday. The protest was organised by The Voices for the Animals group as part of their Speak Day of Action.

One of the protesters, Sarah Castlemaine, 23, a student at Oxford, said: "The animals have no way of speaking so we are here to speak for them. The laboratory flies in the face of modern day society. We cannot stand for it."

Jacqueline Chambers, of East Oxford, who was accompanied by her two children, Tom, seven, and Georgia, five, said: "I want my children to know what's going on here as they are the people of tomorrow. We must continue to fight against plans such as this. The university cannot just be allowed to get away with this."

Teacher John Hanlon, 42, who travelled from Northampton for the demonstration, said: "It's totally barbaric for the university to be doing this. We need to do all we can to stop it."

Cambridge University was forced to abandon plans to build an animal research facility after a similar campaign.

Following the demonstration in Broad Street, the protesters walked to the university science area, but were not allowed by the police to get near the proposed laboratory site.

Police said the demonstrators had initially agreed to leaflet the city centre, not to hold a march.

Chief Supt David McWhirter said officers had been forced to give them a "prescribed route" via Parks Road, Keble Road and St Giles to minimise the disruption to the public and any potential damage to university buildings.

He said: "Thames Valley Police is quite clear in its mind that there must be a balance between peaceful protest and unlawful action and we will not tolerate the latter."

He said the police recognised that protesters had a right to march but the aim of the police was to reduce the impact on everyone else.

He added: "What is essential is that the protesters work with us; if they do not that brings tensions between themselves and the police, which we would always seek to avoid."

A man has been charged with assaulting a police officer during Saturday's demonstration. Mark Hughes, of Hartley Road, Luton, will appear before Oxford magistrates on Monday