Chile declared a state of emergency on Friday as officials said 10 people were feared dead in forest fires in the central Valparaiso region, where blazes are threatening hundreds of homes.

Officials there gave the "preliminary" toll as Chilean President Gabriel Boric decreed "a state of emergency due to catastrophe, in order to have all the necessary resources" to fight the fires.

The blazes are concentrated in the Vina del Mar and Valparaiso tourist regions, where they have ravaged hundreds of hectares of forest and forced evacuations.

Around 480 hectares have already been burned in Valparaiso alone, according to CONAF, the Chilean national forest authority.

The fires are being driven by a summer heatwave and drought affecting the southern part of South America caused by the El Nino weather phenomenon, as scientists warn that a warming planet has increased the risk of natural disasters such as intense heat and fires.

As Chile and Colombia battle rising temperatures, the heatwave threatens to sweep over Argentina, Paraguay and Brazil in the coming days.