In the 1970s and 1980s, photographer and activist Claudia Andujar was living among Brazil’s Yanomami indigenous people, whose villages are dotted across 9.6 million hectares of the Amazon rainforest. “At the time they had known very few people outside their own community,” Andujar says slowly when we meet in her modest apartment in central São Paulo, running her hands over the tabletop as she remembers the details. “They had never seen a camera before.”

Andujar immersed herself among the Yanomami, learnt their belief system and the threats they faced from disease, deforestation, invasion and exploitation. As she gained knowledge, she felt able to photograph them. “I wanted my work to come from a position of respect,” she says. The aim was that the images would not be those of an outsider looking in, but rather expressive of Yanomami culture, in which the separation between human and forest is blurred and the relationship between people and spirits is paramount.

Andujar approximated this cosmology in her photography with a plethora of methods, both high-tech and low, from the use of colour filters and infrared to smearing Vaseline across the camera lens. In one work from the Reahu series, named for a ceremony to honour the dead, she photographed a shaman, his eyes rolled back, his body lit by firelight. The forest is pitch black behind him. The man had spent several days taking yãkõana, a hallucinogenic powder. The Yanomami believe the drug facilitates communication with the xapiripë, forest spirits. As they inhale it, supernatural beings are said to appear from the mountains as streaks of light. At the top right of Andujar’s image, a bleached-out ball of light of unknown source hovers in the darkness.

“This guy here is far gone, he is travelling beyond this world,” Andujar says as we leaf through a book of her work. “This is what I wanted to show using the light, slowing down the shutter speed to approximate his experience and emotions and atmosphere of the moment.”

Although we are talking a fortnight from her 90th birthday, Andujar refuses to give up on the now 50-year-old promise she made with the Yanomami to fight for their cause. With Brazil under the cosh of Jair Bolsonaro’s far-right presidency and Yanomami land facing renewed threat of deforestation, her mission has greater urgency than ever. One fulfilment of this promise is a touring exhibition that opens at London’s Barbican on June 17 and will go on to New York.

Bruce Albert is a French anthropologist who met Andujar in the late 1970s. “I was staying the night at a base camp on the edge of Yanomami territory accessible by road,” he says. “Half asleep I heard the sound of a Volkswagen Beetle. I dreamt I was back in Paris. But it was real, stepping out of this little car was the white woman I had heard the Yanomami speak of so much.”

Albert is clear that Andujar’s work is distinguished from that of photographers such as Sebastião Salgado and Raymond Depardon, who have also shot indigenous communities, because of the time she spent with the Yanomami, who number about 38,000. “The people in her photos are rarely staring at her as she takes the picture,” he says. “In many of the images it seems they have forgotten her presence, it’s as if she has almost become one of them.” She became known as “mother” in the villages. “I had my own hammock in the communal house,” Andujar says. “I visited the communities alone mostly; I didn’t go there with a group of other white people.”

Her close relationship was built through a drawing programme with the Yanomami, initiated in 1974. The result was hundreds of felt-tip pen sketches, in which inhabitants of the Catrimani river region describe aspects of their world view, from the Raharari, a mythical animal that inflicted flooding on their ancestors, to their encounters with the napëpë, the non-indigenous people, which they believe will herald the end-days.

Thyago Nogueira, who curated the touring exhibition, says that some have questioned how much control the Yanomami have in their relationship with Andujar, “but that question only comes from Europeans”. “There is an insistence in reading her as a white woman photographing indigenous people in Brazil,” he says, “framing her in a very colonial perspective, but her work developed as she learnt from them . . . Brazilians tend to recognise that the indigenous situation is so traumatic, so violent, anyone who is fighting for them is deserving of respect.”

Andujar was born Claudine Haas in Neuchâtel, Switzerland, in 1931, the only daughter of Germaine Guye, a Protestant, and Siegfried Haas, a Hungarian Jew, but the family returned to her father’s native Transylvania when she was very young. It was a tragic decision: in 1944, as the German army advanced on their city, Claudia and her mother managed to escape to Switzerland, but Siegfried and his extended family were not so lucky. They were transported to the Dachau and Auschwitz concentration camps. She returns to the story several times in our conversation, her voice flat, going over the details again and again, until she says simply: “They all died.”

When the war was over, Andujar went to New York to study humanities at Hunter College, later joining her mother in Brazil. In the US she had changed her name to Claudia — a signal, she has said, of a new life, her childhood too fraught with tragedy. Her surname comes from a short marriage to a Spanish refugee.

Andujar took up photography on arrival in São Paulo in 1955. “Taking photographs was at first a way of communication because I didn’t speak Portuguese. It allowed me to see Brazil beyond São Paulo,” she says. Charismatic, with a good eye, she quickly received commissions from titles including Life magazine, making work about indigenous communities in Brazil. Then, in 1971, she photographed the Yanomami for the first time.

Her photographs from that trip exposed the lie that the northern regions were “empty”, peddled by the military dictatorship to excuse the Amazon’s exploitation by the logging and ranching industries. Andujar returned north the following year on the first of many trips funded by overseas grants, some lasting more than a year. She found the Yanomami’s situation becoming more precarious because of construction and disease.

A new road was being built from the Colombian border to the east coast, carving the indigenous lands in two. In one of Andujar’s photographs from 1974, the body of a man killed during construction is shown laid out across two wooden crates. By the late 1970s, measles and malaria were rife, wiping out whole villages where inhabitants had no immunity. Another image, shot through a shocking pink filter, depicts a young man, his eyes closed in sickness, shrouded in his hammock. “There was so much disease, all brought by the white men. I experienced so much death when I was with them,” Andujar says.

In Yanomami tradition, when someone dies, all their possessions must be disposed of in a process of “forgetting”. By rights a photograph would be anathema to this, but such was the trust, and the understanding that their plight needed to be exposed, the community allowed Andujar to take pictures of numerous funeral rites. This is the faith she refuses to breach. When she sells prints, the money is split equally between her, her Brazilian gallery and Hutukara, a Yanomami-run non-governmental organisation.

The photographs tested the patience of Brazil’s military dictatorship and in 1977 Andujar’s permit to travel into the Amazon was revoked. Files in Brazil’s National Archives show she was being monitored by the regime, one report deeming her activities “unnecessary” to “national interests”. She was scared and frustrated. “But I had to accept it, there was nothing I could do.”

Andujar’s return to Brazil’s north after the dictatorship fell marked a turning point. At a medical centre on the edge of the forest, she and her colleagues initiated a mass vaccination programme. “At that point all the health programmes were concentrated in the centre of Brazil,” she says. “I stopped photography because I got so involved in all this political work. I became an activist.”

But the practicalities of the programme meant she had to pick up her camera again. Traditionally, it is taboo to use a Yanomami person’s name, so to identify who had been treated and who had not, Andujar gave each patient a number, photographing them with it etched on a plaque. Hundreds of Yanomami faces stare blankly back at us, with none of the life of Andujar’s previous images. The similarities between these pragmatic images and the registration photographs taken at the Nazi concentration camps struck her.

“When I saw what was happening to the Yanomami people, this genocide,” she says, “it reminded me of what happened to my family during the war. My own history, what happened to me and my family, influenced my life and work very much.” Returning again to the past, Andujar tells me about Gyugi, a boy from her childhood — her first love, her first kiss — who also died at the hands of the Nazi regime.

At the opening of her show in Paris last year I spoke to Davi Kopenawa, a Yanomami shaman who Andujar has worked with on advocacy. “For me and the Yanomami,” he said, “it is important for the white people to see everything related to us: where we live, the language we speak, how we live and experience the world. To see what the original people of the forest have been through, to know our reality.”’

The Yanomami population is very young, the older generations killed by previous epidemics, so they weathered the Covid-19 pandemic relatively well. But soaring gold prices have led to a surge in illegal mining on their land, on top of deforestation, which displaces them. Videos have emerged of Yanomami being shot at by organised gangs. This all appears to be done with the tacit approval of the Bolsonaro government, which has been pushing through a bill to legalise such commercial extraction. On his first visit to the territory in May, the president claimed the Yanomami would not be forced to accept mining of their land. Yet with environmental protection laws diminished and budgets cut since the president came to office in 2019, activists have little hope of any real change.

Andujar tells me that although she is no longer able to take photographs, she can use her past work, and her past, to help the present. “The Brazilian government has absolutely no interest in the indigenous people,” she says, leaning forward. “This moment is the worst it’s ever been.

“I thought through my photography I might get the world to know who the Yanomami are, that it might help them,” she adds. “They allowed me to take their photographs, they welcomed me into their lives, so I will continue speaking out for them until the end of my days.”

“Claudia Andujar: The Yanomami Struggle” is at the Curve Gallery, Barbican Centre, London, June 17-August 29

Follow on Twitter to find out about our latest stories first