The army in Brazil has been sent in to fight forest fires which are spreading out of control in an area of the northern Amazon rainforest.
By Tom Gibb
BBC correspondent in Brazil
The fires are being fuelled by exceptionally dry weather and high winds being blamed on the El Nino climate effect.
In the last four days, satellites have detected 686 fires in the northern state of Roraima, most of them started by farmers who burn the land in preparation for planting when the rains start.
But high winds and exceptionally dry conditions have allowed the fires to spread out of control.
El Nino conditions
Already, the edge of the forest reserve of the Yanomami Indians, one of the Amazon's largest hunter gatherer tribes, is burning.
Farmers burning off land cause many fires at this time of year
Firefighters have been dropping water from helicopters and nearly 900 firemen are now being deployed, with the army co-ordinating their efforts.
Roraima's provincial capital, Boa Vista, had a smoke haze from the fires hanging over it on Monday.
The dry conditions have been blamed on El Nino, a warm current in the Pacific Ocean which periodically causes climate changes across the region.
But scientists are also worried that excessive destruction is drying out the world's largest rainforest, making it more vulnerable to fires.
The last big fire in the northern area of the Amazon was in 1998, and was only put out by rain.
Weather forecasters are not predicting rain for at least another week.