"With pride we receive your Royal Highness," Indian Chief Coxini Karaja told the heir to the British throne, who flew by helicopter to a remote inland airstrip on the final leg of a two-day trip to Brazil, before heading to Mexico.

Charles arrived on Bananal Island - which sits on the eastern tip of the Amazon - from Rio de Janeiro.

Bananal, named after its prolific banana trees, spans an area almost twice the size of Belgium in Brazil's interior.

The island sits in a transition area between three major ecosystems - tropical rain forest, savanna and swamp, a fertile breeding ground for diverse flora and fauna and home to piranhas, pumas, jaguars and armadillos.

That made it a fitting final stopover in Brazil for Charles, a fervent environmentalist. The prince, wearing brown suede shoes, nodded and smiled as he debated conservation issues with Coxini Karaja to the furious flash of cameras.

"This visit is an encounter between defenders of the environment," said Karaja. Karaja asked the prince for more help from Britain in preserving the environment while Charles was curious to know if the Karaja tribe had a lot of land.

TWO THIRDS OF ISLAND FLOODS DURING RAINS

The Karaja is the most populous tribe of the 3,000 Indians that live on Bananal, many of whom believe they were born of the rivers that isolate the island and flood two thirds of it in the rainy season.

But Bananal's thick forests and shallow swamps are also the backdrop to a tug-of-war between eco-tourism, conservation and indigenous land rights.

While Indians want the right to hunt and fish as they wish on their ancestral homeland, environmentalists and the Brazilian government want to preserve the area's valuable biodiversity and make use of its resources with such projects like the rain forest station.

To view that rain forest research center, Charles strolled along a wooden walkway to take a boat down river as photographers waded through the boggy marshland below.

At the Cangucu rain forest station, scientists conduct research into carbon sequestration, a process that seeks to offset the harmful greenhouse effect of carbon emissions by producing oxygen through photosynthesis.

Cangucu is financed by a gas-fired power station in South Wales, owned by AES Barry.

At the station, a collection of modern-day treehouses, Charles visited an Amazon turtle project, where students and scientists work to ensure that more of the 40 to 160 eggs laid by each turtle every year survives long enough to hatch.

The Amazon turtle is the largest and most endangered of the turtle family, weighing up to 60 kilograms.