Police in Brazil have given more details about an ongoing operation to protect one of the Amazon basin's most isolated Indian tribes.
Officials in Rio Pardo found Indian villages, but no Indians
They said they had arrested 29 people in the north-eastern Mato Grosso State for encroaching on the lands of the Rio Pardo tribe, named after a local river.
Those detained included businessmen, loggers and land-squatters.
Almost nothing is known about the Rio Pardo - not even the language the tribe of hunter-gatherers speaks.
"There are no more intruders in the region," Marcos Antonio Farias, federal police chief in the Mato Grosso capital Cuiaba, told Reuters news agency.
Those arrested are believed to be members of an association of landowners seeking to develop the vast area into farmland.
The Rio Pardo group is so isolated that its existence has been hard to confirm.
However, Brazilian television earlier this week showed the first pictures of several members of the tribe, who were seen cutting a tree trunk.
Earlier this year, experts found abandoned villages as well as vital hunting implements and supplies of fruit and nuts believed to be used by the tribe.
Brazil's federal Indian bureau (Funai) head Sydney Possuelo has warned the tribe would be "annihilated" if measures were not taken to protect them.
Local rights groups have also called on the Brazilian government to create a reserve to protect the Indians' land.