The Brazilian government will begin using a plane equipped with body-heat sensors to locate — and protect — uncontacted Indian tribes in the Amazon, officials said Tuesday.

Locating the tribes will help the National Indian Foundation create reserves where loggers or farmers are barred, Antenor Vaz, who heads the work on isolated tribes for the agency, known as Funai.

"It will be an excellent new tool that will enable us to help them," Vaz told The Associated Press.

• Click here for photos of an uncontacted tribe.

Intruders clearing lands used by tribes in the Amazon rain forest comprise one of the biggest threats to the isolated peoples.

The technology will also help Funai avoid endangering the tribes through contact with its own workers.

"It will enable them to locate a tribe ... without exposing them to the risk of 'Western' diseases such as flu to which uncontacted or isolated groups have no immunity," said Fiona Watson, the Brazil coordinator for London-based Survival International, which works to protect indigenous people around the globe.

Watson said that until now, about the only way to discover where the tribes are located has been to walk the forest and find them, which she said was "like trying to find a needle in a haystack."

Funai will mount the heat sensors on a government plane normally used to monitor deforestation. Vaz said it was not clear when the effort would start.

The planes will crisscross the Amazon at high altitudes to ensure there is no disruption in the lives of the uncontacted tribes.

Most of Brazil's Indians continue to live in the jungle and maintain their languages and traditions. Many have fought for decades to keep or regain their ancestral lands.

Brazil's 1988 constitution declared that all Indian ancestral lands must be demarcated and turned over to tribes within five years.

While that process has yet to be completed, about 11 percent of Brazilian territory and nearly 22 percent of the Amazon is now in Indian hands.

In May, Funai released photos of an isolated Amazon tribe firing arrows at an overflying plane.

Government officials had known of the group for some 20 years and only revealed its existence then to call attention to the plight of uncontacted tribes who are in danger because of illegal logging.