Brazilian authorities have admitted that the Amazon's Awa, "Earth's most threatened tribe," are outnumbered 10 to one in just one of their reserves, Survival International said Thursday.

Survival International, a leading advocate for tribal peoples' rights worldwide, said officials admitted "the scale of the emergency" after receiving over 20,000 messages of protest following the launch of its drive to save the Awa from "imminent extinction" late last month.

It pointed to a Brazilian government survey estimating there could be "up to 4,500 invaders, ranchers, loggers and settlers" occupying just one of the four territories inhabited by the Awa, whose total population stands at no more than 450.

Last month, the rights group launched a major campaign spearheaded by Britain's Oscar-winning actor Colin Firth to focus world attention on the plight of the Awa, saying they were threatened with "genocide" and "extinction."

The campaign also aimed to persuade Brazilian Justice Minister Jose Eduardo Cardozo to send in federal police to clear out the loggers, ranchers and settlers invading Awa lands, and keep them out.

Survival said the new head of Brazil's National Indian Foundation (FUNAI), Marta Azevedo, confirmed that the threat to the Awa was now her agency's top priority.

"The Awa tribe's land is being destroyed faster than any other Amazon tribe. As the rainy season ends, one of their main hunting areas is now being targeted by loggers. An Awa man named Armadillo said today, How will we live without the forest?," the group said in a statement.

"Brazil is one of the world's most important countries with one of its most dynamic economies, and it certainly has the resources to protect Awa land. Can it deliver?" said Survival Director Stephen Corry. "If not, and the Awa are destroyed, then is this new economic miracle' just for the rich and powerful?"

According to Survival, there are roughly 360 Awa who have been contacted by outsiders, many of them survivors of brutal massacres, along with another 100 believed to be hiding in the rapidly-shrinking forest.

FUNAI estimates that there are 77 isolated indigenous tribes scattered across the Amazon. Only 30 such groups have been located.

Indigenous peoples represent less than one percent of Brazil's 192 million people and occupy 12 percent of the national territory, mainly in the Amazon.