A remote tribe living amid the depths of the Amazon rainforest is facing extinction at the hands of loggers, campaigners warn.
Brazilian officials in Rio Pardo found Indian villages, but no Indians
Armed loggers working in Brazil's vast forests have driven the tribe from several villages, according to Indian rights group Survival International.
Survival urged Brazil's government to act quickly to protect the tribe.
The group is angry that a judge lifted a ban and allowed loggers back into in tribal forest.
'Forced to flee'
Government experts on indigenous Brazilians have discovered abandoned villages as well as vital hunting implements and supplies of fruit and nuts.
The finds indicate that the Indians were forced to flee their homes in the Rio Pardo region at short notice, Survival International says.
"These loggers are very well armed and they are intent on getting a quick fix out of the forest," Fiona Watson of Survival International told the BBC.
Sydney Possuelo, head of the isolated Indian department of Brazil's federal Indian bureau (Funai), said the tribe would be "annihilated" if nothing is done to protect them.
The Rio Pardo Indians are so isolated that their very existence has been hard to confirm.
For years neighbouring tribes have reported hearing the sounds of humans mimicking animal noises deep within the forest.
Gold diggers and loggers moving through remote parts of the Amazon have also spoken of the feeling that they are being watched from within the foliage.
"They [the tribe] almost certainly will know what is going on," Ms Watson said.
"Past history will have taught them that any invasion of their lands by the outside world is almost inevitably fatal for them."
Under a Funai protection order issued in 2001, loggers were banned from a 166,000 hectare (410,000-acre) area of rainforest.
But a logging company succeeded in reversing that order earlier this year, convincing a senior judge that the order would endanger its business.
The Awa Indians recently won the right to their traditional land
The judge opened the area to loggers and banned Funai from the area.
"This is like putting a gun in the loggers' hands to kill Indians," Mr Possuelo said.
Survival International has run a number of high profile campaigns to aid other Indian tribes, winning officials recognition of their lands from Brazil's authorities.
About 700,000 Indians live in Brazil, more than half of them on designated reservations.