Some 1,200 troops and 500 firefighters have joined the effort to control Chile's worst forest fires in decades.
A state of emergency has been declared in a vast area south of the capital, Santiago.
The blazes began over a week ago and spread quickly in the dry and particularly hot summer that many South American countries are experiencing.
President Michelle Bachelet said she had asked for help from countries with experience of forest fires.
"The firefighters are doing all that is humanly possible," she said.
But Chile has "practically exhausted its capacity to fight the blazes", Ms Bachelet added.
She asked for help from her French counterpart, Francois Hollande, who is visiting Chile.
The authorities also requested planes and helicopters from the United States, Canada and Mexico and neighbouring Argentina, Brazil, Uruguay and Peru, EFE news agency reported.
There were more than 100 uncontrolled fires in central and southern Chile until a few days ago.
The latest report from Chile's Forestry Agency (Conaf) says most of them have now been controlled.
There are now 39 fires, affecting mainly the O'Higgins and Maule regions.
Hundreds of people have been evacuated from their homes.