"Four Paws is demanding an immediate break with this cruel tradition, in which many people get hurt and many bulls suffer a painful death every year," the international organisation said in a statement on its Bulgarian website.

"This kind of entertainment has nothing to do with culture and should be abolished," Vier Pfoten campaign director Gabriel Paun added.

The run -- which sees bulls rushed along Pamplona's streets and then forced to fight in the arena during the San Fermin festival -- was a form of cruelty against animals that would be punishable with prison in other European countries, he noted.

"Before the beginning of the event, so called 'picadores' on horses torment the bulls. They ram spears into their backs, slit their necks and panic them by giving electric shocks and beatings with sticks," the group said.

"Badly hurt, (the animals) are driven into the bullfighting arena, in order to be tortured slowly to death by the torero to great applause from the audience."

The 13,000 bulls killed each year at bullfighting events have given Spain "a bad reputation," Vier Pfoten went on, citing a Spanish online poll in which 80 percent of people supported a ban on the practice.

Bullfighting is already banned in two autonomous regions of Spain: Catalonia and the Canary Islands.

However, the massive crowds of thrill-seekers who flock every year to the San Fermin runs and other bullfighting events are also a boon for the tourism industry, boosting revenues.