Naked Protest by Animal Rights Campaigners at Pamplona Bull Run [SLIDESHOW]

Animal rights protesters paraded naked in the run-up to the annual running of the bulls in the Spanish town of Pamplona.

Painted head to toe in black and red, the protesters stepped out on to the streets of Pamplona at the start of the seven-day San Fermin festival, lay on the ground in a town square and arranged their bodies to spell the words "stop bullfighting".

The event, which attracts hundreds of brave or stupid people to run ahead of the bulls as they charge through the town's narrow streets, has its roots in the 14th century.

It has boomed into an international tourist event, with people coming from all over the world to test their courage by running as close as they can to the rampaging livestock.

The event has been condemned by animal rights campaigners and groups such as Peta for the treatment of the animals, which are enraged and scared by the crowds jeering them on. The bull run serves to transport the bulls to the ring, where they will be killed in a bullfight.

A Peta spokesman said: "Torturing and killing a defenceless animal should not be celebrated as a tradition. People have always tried to use tradition to justify horrible things, such as child labour and slavery. But tradition doesn't make something right."

In 2002, Peta launched the annual Running of the Nudes through the town's streets. Campaigners take part in the naked protest, running in just horns and a red scarf. The event has gained popularity over the years, with as many as 1,000 taking part in the last run.

The bull run also has a human cost, with an average of 250 people injured ever year. Fifteen people have been killed, the most recent being 27-year-old Daniel Jimeno Romero in 2009.

Bull runs are held throughout Spain and Portugal, although the recent banning of bullfighting in some parts of Spain appears to show the tide turning against traditional bloodsports.