In a historic vote last month the Spanish parliament's commission for the environment, agriculture, and fisheries declared its support for The Great Ape Project - a proposal to grant rights to life, liberty, and protection from torture to our closest nonhuman relatives: chimpanzees, bonobos, gorillas and orang-utans. Other countries, such as New Zealand and the UK, have taken steps to protect great apes, but no national parliament has declared that any animal could be a person with rights.

Keeping great apes in captivity will be allowed for purposes of conservation only, and then under optimal conditions for the apes. Moreover, the resolution recommends that Spain take steps in international forums to ensure that great apes are protected from maltreatment, slavery, torture and extinction.

Paola Cavalieri and I founded The Great Ape Project in 1993 to break down the barriers between human and nonhuman animals. Researchers such as Jane Goodall, Diane Fossey and Birute Galdikas have shown that great apes are thinking, self-aware beings with rich emotional lives, and thereby prepared the ground for extending rights to them.

If we regard human rights as something possessed by all human beings, no matter how limited their intellectual or emotional capacities may be, how can we deny similar rights to great apes? To do so would be to display a prejudice against other beings merely because they are not members of our species - a prejudice we call speciesism, to highlight its resemblance to racism. The Spanish resolution marks the first official acceptance of that view. The use of the term "slavery" in relation to animals is especially significant, for it has been assumed that animals are rightly our slaves, to use as we wish, whether to pull our carts, be models of human diseases for research, or produce eggs, milk, or flesh for us to eat. Recognition by a government that it can be wrong to enslave animals is a significant breach in the wall of exclusive moral significance we have built around our own species.

While Spanish parliamentarians were sympathetically considering the rights of animals, in Austria 10 leaders of lawful animal welfare organisations were beginning their fifth week in prison. Police had roused people from their beds, put guns to their heads and seized computers and files, disabling the animal-rights movement on the eve of it launching a new initiative to enshrine the protection of animals in the Austrian constitution. The leaders are being held without charge under a law aimed at members of criminal organisations such as the mafia, and a court has remanded all 10 to be held until September.

One, Martin Balluch, has been given a 1,500-page police file to justify his arrest. In the file his name is mentioned only three times, all in connection with media interviews or articles. Ironically Balluch, a brilliant man with doctorates in both physics and philosophy, is one of the foremost spokesmen in the worldwide animal rights movement for pursuing the nonviolent, democratic road to reform. In recent years, Austrian animal welfare organisations have been remarkably successful in persuading voters and legislators to support laws phasing out cages for egg-laying hens, cages for raising rabbits for meat, and raising animals for fur. As Balluch writes: "A law banning a whole industry does far more economic damage to the animal abuse industry than anything else the animal movement could do."

The police persecution appears to be an attempt by the conservative party, which controls the ministry of the interior, and its animal industry supporters to strike back at a legitimate, peaceful challenge to the way we treat animals. That this can happen in a European democracy is shocking.

· Peter Singer is professor of bioethics at Princeton University and author of Animal Liberation

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