Violent clashes at an animal rights demonstration in Oxford saw protesters break through metal barricades and hurl missiles at riot police.

Police in South Parks Road hold back protesters at Saturday's march

Five people were arrested during the protest on Saturday near the controversial £18m animal laboratory in South Parks Road.

Protesters issued chilling warnings to all those associated with the new lab, during the first major protest since building work resumed in November.

About 400 protesters with klaxons, sirens and megaphones shouted "Stop the Oxford animal lab" on the march from Broad Street to South Parks Road. A handful wore scarves to hide their faces.

A High Court injunction prevents protesters from entering a 35-metre no-harassment zone around the building site.

More than 50 police officers, some wearing riot gear, stopped the march about 100 yards from the half-built laboratory.

Protesters then pushed forward, knocking over a metal fence and scuffling with police, to try to get closer to the building.

Mel Broughton, spokesman for animal rights group Speak, told the crowd: "Now it is time to fight. We must take this chance, we must do what is necessary -- and if that means some of us being arrested, then so be it.

"The time has come for fighting, not talking. If we need to, we have got to tear that place down with our bare hands.

"You have got every opportunity to enter this city any time of day or night and they won't stop you. They are going to have to worry about what will happen next."

Mr Broughton told police: "Everybody who works at this university has made a fundamental mistake and you really are going to regret what you have done today.

"If we have to go to prison, then so be it. We are going to fight like we have never fought before."

Work at the complex resumed less than two months ago, after a 16-month delay which began when contractors pulled out after being threatened by members of the Animal Liberation Front.

After the march, an anonymous protester said: "The police presence has been over the top. They are just flexing their muscles all the time, it's bound to cause confrontation by holding people back. We were fully expecting to go closer to the lab."

Officers were drafted in from across the Thames Valley, along with City of London mounted police and officers with recording equipment to monitor the crowd.

Assistant Chief Constable Alex Marshall, who oversaw the operation, said: "Although the majority of protesters behaved well, it is disappointing that the organisers failed to provide stewards, as we had asked them to do, and unacceptable that my officers were subject to violence.

"All the resources put into the operation have been put to good use because of the disruptive and antagonistic nature of a number of the crowd. A lawful protest, which is what had been discussed at meetings with the organisers, should not involve participants wearing masks to conceal their identity and the removal of barriers put there to ensure public safety."

The five arrested for breaches of public order were released on bail until Thursday, January 26. They are barred from entering Oxford. Two are from Essex and others from Northampton, London and Kent.