Measures to protect scientists who experiment on animals are being considered by the government.
Tougher sentencing for protesters who publish the personal details or target the homes of people associated with animal testing are among proposals being studied by Home Office officials.
Home secretary Jack Straw said new legislation was being studied to enable police to take stronger action against animal rights activists. "Many of us would not be able to lead healthy lives were it not for the pharmaceuticals companies being able to test their drugs on animals," he said.
The issue has become more urgent after a series of arson attacks on cars belonging to staff members of Huntingdon Life Sciences, a research complex in Cambridgeshire that has become the focus of a national campaign by anti-vivisection protesters.
These raids followed the release of four people on conditional bail after being charged by Cambridgeshire Constabulary with inciting others to commit criminal damage, grievous bodily harm and harassment in relation to employees and associates of HLS.
Mark Matfield, executive director of the Research Defence Society, said the police needed to target those people who distributed lists of scientists' personal details.
While the number of animals experimented on fell slightly to 2.57 million last year, the number of transgenic animals, mostly rodents, increased by 14 per cent between 1998 and 1999.
Among those calling for a tougher stance was Andrew Blake, founder and director of the pressure group Seriously Ill for Medical Research.
"These scientists are trying to do a job that is wanted by people like myself. It is terrible they are not being protected," he said Mr Blake, who is wheelchair-bound by the genetic disorder Friedreich's Ataxia, is a shareholder in Huntingdon Life Sciences and has been picketed at his home by protesters. He suggested labelling prescription drugs that have been tested on animals.
"People don't realise that there is no other way of developing drugs than to test them on animals. Labelling would bring that message home," he said.
Andrew Tyler, director of the pressure group Animal Aid, agreed with a labelling policy, though for opposite reasons.
He said animal models compared badly to humans and that many medicines developed using animal experiments are dangerous or ineffective.
"It would be excellent if prescription drugs were labelled - it would provoke greater public debate," said Mr Tyler.