A further 1,000 members of the Yanomami tribe in Venezuela are believed to have caught the flu, the indigenous peoples rights group said.
It is feared the flu could sweep through the area and kill many more Yanomami as the Indians have little resistance to introduced diseases.
About 32,000 Yanomami live in the Venezuela-Brazil border region and form the largest relatively isolated tribe in the Amazon.
Survival director Stephen Corry said the situation was critical and the Venezuelan and Brazilian governments must act immediately to halt the epidemic and improve health care for the Yanomami.
“If they do not, we could once more see hundreds of Yanomami dying of treatable diseases. This would be utterly devastating for this isolated tribe, whose population has only just recovered from the epidemics which decimated their population 20 years ago,” he said in a statement.
About 20 per cent of the Yanomami tribe died from flu, malaria and other diseases in the 1980 and 1990s when goldminers invaded their land, Survival said.
The Venezuelan government has closed the border and sent medical teams.
The H1N1 virus — the correct medical term for swine flu — has spread globally and killed nearly 5,000 people since appearing early this year, according to the World Health Organisation.
