By Isabel Murray Sao Paulo

Hundreds of Brazilians woke up at the crack of dawn on Saturday just to take off their clothes in the middle of the biggest public park in South America's largest city.

Their task - to pose for a collective nude photo by the American photographer Spencer Tunick, in Ibirapuera Park in a performance that was part of the Sao Paulo Art Bienal.

There was disagreement as to the number of participants. According to the photographer's team, 1,200 people showed up for the event.

Spencer Tunick directs the naked throng

The local metropolitan civil guard calculates 400 people removed their clothes in front of the photographer's lenses and before a multitude of journalists and curious onlookers. The great majority of the volunteers were men.

The models who signed up over the internet, began to reach the park at 5am, as had been requested by those organising the event.

Although Tunick insisted that what he does is a serious work of art, the atmosphere was one of a lot of joking around and complete euphoria.

"I had already had a load of pictures taken without trousers just to have a laugh with my friends," said Marcos, 22, who managed to convince two more friends to come along with him. "So this here is going to be even funnier."

Some people said that they had come along because of the unheard of aim, such as sculptor Majo Ferreira, 31. "I think Spencer's work is marvellous, and I want to be part of it".

Applause for artist

"You feel a bit embarrassed, it's true," confirmed Suzy, a 32 year-old architect.

It was still dark when the first interruption occurred. A reporter from a TV entertainment show turned up without any clothes, and tried to interview members of Tunick's team, who didn't find the joke at all amusing.

The transvestite didn't undress, but the reporter did

The police took the reporter to the area reserved for the press and he remained there naked. During the photo-shoot, he along with two other reporters (including one transvestite), took part in the photos as models.

It was not until the sun rose that the photos began. Standing on top of a ladder, Tunick gave his instructions to the group, with the help of a translator. Every comment he made was applauded with enthusiasm.

Watching hundreds of people take their clothes off in public, without any concern over aesthetics or any obvious shame is a strange scene. And on top of this, between each shoot, the group wandered around naked inside the park, waving to the journalists.

My work is a celebration of life Spencer Tunick

Tunick's photos do not have any sensual or erotic attraction. Many critics compare them to those photos taken in concentration camps during the Second World War. The artist rejects this comparison.

"You could also think of the massacres in Rwanda, Bosnia, the Armenian holocaust, or in disasters such as earthquakes or landslides that rip the clothes off 30 thousand people", he told the BBC.

"There are so many ways to think of a mass of bodies as death, but what I'm dealing with here is life. My work is a celebration of life."

During the photos, Tunick asks people to avoid looking directly at the camera, or smiling. The result is weird and a bit shocking.

Sex object

Tunick has already visited 30 countries taking pictures of naked people for the project Nude Adrift. Brazil is the last stop on the tour.

Brazilians take their task lying down

Tunick said "I guess people want to do something else with their bodies. Using your body to make a shape as an art object is a very pure experience and it's a wonderful thing.

"I don't use the body as a sex object, but as an art object. And the body is used in a new way in my work. It's used to make a mass sculpture. It's liberating, it's an unbelievable situation to be in, and I think other people feel the same way. "

All the volunteer models will receive a copy of the photo which Tunick judges to be the best one from the photo-shoot. And the photographs from the entire tour will be on display in New York at the end of this year.