An isolated native tribe from the Amazon rainforest has made its first contact with the outside world, driven by desperation after an apparent "massacre" at their village.

A handful of adult tribesmen met with residents of a modernized native settlement near the Brazil-Peru border in late June, according to a video released by Brazil's National Indigenous Foundation, FUNAI. The agency says the Amazonian natives are from one of an estimated 77 uncontacted native tribes living in the Amazon. They first emerged from the forest on June 29, then appeared again on June 30 to meet with FUNAI representatives. The second encounter was captured on video and uploaded to YouTube.

The natives appear almost entirely naked and carry crude weapons, including machetes, spears and bows. In the video, they can be seen accepting bananas from a native of the nearby settlement. Later in the video, two tribesmen enter the settlement and carry away a modern axe and a brightly-coloured cloth.

Speaking through a FUNAI interpreter, the natives said they were driven to seek help after disease and attacks from the outside world decimated their village.

"The majority of old people were massacred by non-Indians in Peru, who shot at them with firearms and set fire to the houses of the uncontacted," interpreter Ze Correia told the tribal protection group Survival International. "They say that many old people died and that they buried three people in one grave," he added. "So many people died that they couldn't bury them all and their corpses were eaten by vultures."

The tribesmen were seeking weapons and allies, Correia said. They retreated to the forest but came back again after members of their tribe contracted the flu. FUNAI then sent in doctors to treat the infected.

Influenza has been known to wipe out whole tribes in the past.

Survival International describes itself as a "champion" of tribal peoples around the world, and estimates that there are about 100 uncontacted tribes remaining on the planet. An "uncontacted" tribe is a tribe that has had no peaceful interaction with the outside world, Survival International says.

The organization's director says Brazil and Peru should release more funds to keep uncontacted tribes safe from loggers and drug traffickers. "Economic growth is coming at the price of the lives of their indigenous citizens," director Stephen Corry said in a statement on Survival International's website on Thursday. "Their newfound wealth must be used to protect those few uncontacted tribes that have so far survived the ongoing genocide of America's first people."

Contact with the Amazon's elusive jungle tribes is rare. In 2008, a jungle flyover captured never-before-seen footage of an uncontacted tribe near the Envira river in the Brazilian state of Acre.

The tribe FUNAI met with in June first appeared in the same area, along the banks of the Envira.