A doctor whose father was an Oxford University scientist spoke out against animal rights protesters who heckled him for attending a university ceremony.

Dr Jonathan Heatley, a GP, whose father Norman Heatley played a key role in the development of penicillin, was at the Encaenia ceremony yesterday where academics received honorary degrees.

At around 10am, a group of about 25 people protesting about the new animal research laboratory being built at the university gathered at the entrance to the Sheldonian Theatre.

They used a loudspeaker to shout 'shame on you' at Dr Heatley and others entering the building. About an hour later, one man and four women were arrested after they refused to move when asked by police, who had received complaints about noise.

Before the arrests, Dr Heatley tried to reason with the protesters. He said: "I wanted to try and talk to them, to reason with them, but they wouldn't listen. They didn't want to have a discussion, they just shouted at me.

"My father was a research scientist involved with penicillin, which has saved more lives than any other drug. He loved animals. Most scientists working with animals are extremely caring.

"I'm a GP and I'm forever giving out drugs which make people better. I know that drugs can be extremely dangerous if they are not tested.

"If these people drive research abroad, then they will be shooting themselves in the foot. The standards of animal welfare abroad are much worse."

Dr Heatley accompanied his sister for the ceremony because of their late father's connection to the university.

The protesters shouted that the animal laboratory was a torture chamber. Police spokesman Tim Wiseman said that at 11am officers imposed restrictions on the protesters under the Public Order Act and asked the group to move away from the Sheldonian.

When they began a sit-down protest, they were arrested.

He said: "It's unfortunate that the organisers of this protest refused to take opportunities to negotiate with us before today as, with some forward planning, the situation in Cattle Street could have been avoided.

"We must act when such action is causing disruption to others going about their daily business in the city."

The protesters are banned from using megaphones around the laboratory building site in South Parks Road, but were within the law when using one outside the Sheldonian.

Mel Broughton, of protest group Speak, said many academics supported the protests but were afraid to speak out because of the high-handedness of the university.