Almost 25,000 fires have destroyed about 1.5m hectares (3.7m acres) of land and more than 60 houses.

The worst of the destruction has taken place in Bolivia's Amazon and eastern regions, close to the country's border with Brazil.

Smoke from the fires has also delayed numerous flights and forced several airports to close for short periods.

President Evo Morales described the fires as "a natural phenomenon", despite explaining that they were mostly caused by farmers clearing land ahead of the planting season. He said they had lost control of them and the fires had spread rapidly.

Mr Morales also admitted that his government could not fight the fires adequately because it lacked water-bombing aircraft. He said he had requested help from neighbouring Brazil and Argentina.

Indigenous people and small farmers in the Amazon region have traditionally burnt large tracts of land to increase areas of cultivation. But this year, insufficient rainfall and strong winds have made the fires very difficult to keep under control.