Hundreds of campaigners have marched through the streets of Oxford calling for an end to building work at a new £20m research laboratory.
Trouble started during the march through Oxford city
Saturday's rally, organised by the pressure group Speak, saw five people arrested when violence broke out.
The protest was over the building of a controversial new laboratory complex on South Parks Road by Oxford University.
The arrests were for public order offences, after fences were pushed down and missiles thrown.
They five men were released on bail on Sunday until 26 January.
Two of the men are from Essex, one from Northampton, one from London and the other from Kent.
Work on the biomedical facility had been halted in July 2004 after a campaign by animal rights groups.
Construction began again last November with new contractors after other workers claimed to have been subjected to threats and intimidation.
The facility is designed to replace existing university animal housing and laboratory space in a single, modern complex.