Hundreds of anti-bullfighting campaigners, wearing just underwear and with their bodies splashed with fake blood, staged a protest outside Madrid's bullring.

It was the largest such protest ever at the Las Ventas bullring, where fights are taking place this month as part of the city's San Isidro festival, according to protest organisers, Spain's Equanimal and the Dutch-based anti-bullfighting organisation CAS.

Around 250 men and women lay on the ground outside the bullring for more than an hour, encouraged by about the same number of spectators.

"More than 12,000 bulls are killed each year in Spain and the torture must be ended," said Equanimal spokesman Rafael Boro.

CAS director Marius Kolff said: "We hope that in 15 years, bullfighting will have disappeared from the surface of the earth. The battle is already won, as young people don't want it anymore."

The CAS, which is active in Spain, France and Latin America, defends both the bulls and the horses that are part of the spectacle.

The Spanish press on Sunday published photographs of a horse gored by a bull on Saturday at Las Ventas, during a fight by a torero on horseback.

Jose Enrique Zaldivar, a vet who has set up an association of veterinarians in Spain to combat the practice, said the bull suffers in the arena and "we have studies on this" that have been sent to Brussels.

Polls show rising disinterest in bullfighting in Spain, especially among the younger generation, although arenas are regularly filled to capacity for the spectacle, which ends with the death of the bull from a well-placed sword.