A firecracker arched into the air from the balcony of Pamplona's town hall, marking the start of nine days of bullfighting, boozing, concerts and midnight party-going known as the San Fermin festival.

This year, some 1.5 million visitors are expected for the fiesta, which is likely to generate more than 45 million euros (55 million dollars) in income for the Basque city.

Some 10,000 young men in white with red scarves cheered as the festival began at noon, heralding a week in which the bars never close.

The most famous feature of the festival is the daily running of the bulls through the narrow streets of the city to the bullfight ring, preceded by hundreds of daredevils tempting fate. A few people every year are trampled and gored, and at least 14 deaths have been recorded since 1911.

The first run was scheduled for early Wednesday morning.

This year, the tradition has been challenged by hundreds of animal rights activists, who ran through the streets Monday in their underwear after the municipality barred them from demonstrating altogether in the buff.

People for the Ethical Treatment of Animals (Peta) said the bull running is a cruel sport.

"Before being let loose in the streets of Pamplona the bulls are drugged and submitted to various acts of torture to frighten them," Peta said in a statement.

The festival is no more cruel than dozens of other bullfight fiestas all over Spain, but it is certainly the best known, with visitors expected from scores of countries.

For serious bullfight fans, the festival includes "corridas" featuring some of the toughest fighting animals in the country from specialized ranches like Torrestrella, Cabada Gago, Nunez del Cubillo, Dolores Aguirre, Miura, Jandilla and Marques de Domecq.

For many residents, the San Fermin has become more of a nightmare than a fiesta because of the heavy drinking, and they flee to quieter spots.

The town hall has mobilized 1,500 people is spending 2.7 million euros to provide security and clean up the bottles and trash that pile up in the streets every day.

It has also run a series of advertisement warning novices that running with the bulls can be dangerous to life and limb.

Source: Agencies