May 30 (Bloomberg) -- Brazil's National Indian Foundation has discovered an Indian tribe in the Amazon that hasn't had contact with civilization in a rare sighting of the few remaining original inhabitants of the area.

Funai, as the foundation is known, said in a statement that it spotted a group of Indians, six huts and a large planted area near the Envira River, close to the Peruvian border in the Brazilian state of Acre in the western Amazon rainforest. Funai doesn't try to make contact with the Indians and prevents incursions by loggers to ensure their autonomy.

The sighting and the release of photographs by Funai reinforces the need for measures to protect the Amazon from loggers and developers, said David Hill, a researcher at Survival International, a London-based group that defends the rights of tribal people worldwide.

``These pictures are very important to convince governments and companies that isolated tribes do exist,'' Hill said in an interview from London. ``They also send a very clear message: Leave us alone, stay out.''

Photographs showing Indians pointing bows and arrows at a helicopter carrying a team of experts from Funai's Ethno- Environmental Protection Front were published on the foundation's Web site.

``The warriors that were photographed have a strong and healthy appearance,'' Jose Carlos Meirelles Jr., the group's coordinator, said in the statement.

Remote Area

The last photographs of tribes in the area, one of the most remote in the Amazon, were released about 20 years ago, Hill said. Funai officials said they believe there are about 500 Indians in the area where the photos were taken.

The foundation said it didn't know which tribe the Indians belonged to. Meirelles added in the statement that the group has been monitoring four distinct and isolated tribes in that region for the past 20 years. There are about 40 uncontacted tribes in Brazil, Funai said.

There are more than 100 uncontacted tribes worldwide, with more than half living in Brazil or Peru, Hill said, adding they are in danger of being forced off their land, killed and decimated by diseases.

To contact the reporter on this story: Adriana Brasileiro in Rio de Janeiro at abrasileiro@bloomberg.net.

Last Updated: May 30, 2008 10:57 EDT