Campaigners have urged London's Natural History Museum
to halt a botanical research expedition to a remote area in Paraguay, warning it would be "like genocide" for isolated indigenous groups in the region.
Museum staff and scientists from Paraguay are due to set off this week, hoping to find new species in the little-explored forests of the Dry Chaco.
But indigenous peoples' protection groups say the expedition could run into natives who live in the territory, disturbing their way of life and infecting them with potentially fatal diseases.
Benno Glauser, director of the Paraguay-based protection group Iniciativa Amotocodie, wrote to the museum, saying its month-long trip would intrude into the territory of Ayoreo Indians who have never had contact with the outside world.
He included a statement from Ayoreo leaders who live in a town in northern Paraguay. It said: "if this expedition goes ahead we will not be able to understand why you prefer to lose human lives just because the English scientists want to study plants and animals."
"There is too much risk: the people in the forest die frequently from catching white people's diseases. It's very serious. It's like a genocide."
Glauser said there was also danger to researchers as indigenous groups could view them as hostile intruders and attack them.
The museum says it has taken all possible precautions to avoid accidental contact with the Ayoreo groups, and plans to go ahead with the trip.
The Ayoreo are one of the last isolated or "uncontacted" native groups in South America outside the Amazon rainforest.
Until the 20th century, they managed to survive in the depths of the Chaco, a region stretching across Northern Paraguay, Argentina and Bolivia.
But many have been forced out of the forests over the past 50 years by missionaries and progressive deforestation, as cattle ranchers, oil companies and farmers penetrate deeper into their land.
Like other isolated tribes, the Ayoreo also have no immunity to diseases brought in from the outside world. Their plight is similar to that of other groups in Latin American history like the Aztecs who were devastated by diseases like smallpox and measles brought over by colonizing Europeans.
Jonathan Mazower, a spokesman for UK-based Survival International, a non-profit group that works for the rights of tribal people, told Reuters that many Ayoreo who leave the forest catch tuberculosis and other respiratory illnesses.
The most recent contact with the tribe was in 2004, when 17 Ayoreo emerged from the Chaco, revealing that they had spent many years on the run from intrusions into their territory.
Mazower said the museum should avoid their area.
"Because the Ayoreo are nomadic, nobody knows where they are at any one moment," he said. "If the expedition goes ahead into this area, there's no way of guaranteeing that there will be no contact with them.
"The prudent thing to do is to relocate this expedition to another part of the Chaco, which after all is quite a big place."
Richard Lane, head of science at the Natural History Museum, told Reuters the expedition had no interest in contacting isolated groups, and had already taken precautions to avoid accidental encounters.
"When one goes to a remote area, there's always going to be the concern of what's the impact on local people," Lane said, adding that another group of Ayoreo leaders were actually in favor of the expedition.
"They support it because they can learn from it," he said. "And they have offered an elder from the group who is well-informed in traditional knowledge.
"He can go ahead of the expedition into the forest to ensure there will be no unintended contact. There are only a few uncontacted people in this huge area. The chance of coming across them is actually quite small."
(Editing by Steve Addison)