RECENT media reports that the Roslin Institute has halted tests using pig organs for transplant comes as no surprise to the National Anti-Vivisection Society.

For many years we have warned of the potential dangers of transplanting animal organs to humans.

From past experience, we know that several diseases have already jumped the species barrier, including Marburg virus and the hepatitis B virus, while current research suggests that the AIDS virus originated in chimpanzees.

Although drugs exist to prevent organ rejection, these are dangerous in themselves, and there remains a possibility that pigs may host viruses which may not affect them, but could cause disease in another species.

Researchers already know that there are fundamental anatomical differences between human and pig hearts, and have acknowledged the difficulties presented by the expected lifespan of a pig, which is significantly shorter than a human life, yet they have continued to inflict pointless suffering upon animals while unrealistically raising the hopes of sick people.

We applaud the British Medical Association for calling for a system of "presumed consent," whereby organs can be removed from a dead person without permission, unless they have "opted out." It is a practical, humane and realistic solution to the dearth of human organs currently available for transplant.

We hope that other research centres will now follow the Roslin Institute's example and shift their focus away from xenotransplantation and instead look to human solutions for human diseases.

SHELLEY SIMMONS, National Anti-Vivisection Society, Goldhawk Road, London W12 9PE.