SANTIAGO -- A heat wave that has hit Chile this week with record temperatures in some areas and a lack of rainfall has intensified forest fires that have already burned more than 7,000 hectares (17,000 acres)in the South American nation.

Dozens of people have had to evacuate their homes because of the fires and the capital Santiago is under a public health alert due to a cloud of smoke, officials said on Friday.

The state-owned National Forestry Corporation (Conaf) said firefighters were currently tackling 18 fires concentrated in the country's central regions, as well as a smaller number in the south.

Among several localities in the Valparaiso region, around 40 homes have been evacuated and a dozen homes have been destroyed.

Santiago, home to some six million people, woke on Friday to a haze of smoke as a result of a fire in the nearby rural town of Curacavi, where the blaze has devastated more than 1,700 hectares and 120 animals were being removed from the area.

Local authorities issued a public health alert.

"What's being done is to monitor the fine and coarser particles to see how this may affect health," Santiago's government representative, Constanza Martinez, told reporters.

Earlier this week, Chile's government said it was sending more resources to control the spread of wildfires.

The capital recorded its highest temperature this year, 36.7 degrees Celsius (98.06°F) on Thursday, the third highest temperature the city has seen in 111 years, the official meteorology service reported.

Miguel Munoz, metropolitan director of the National Emergency Office, told Reuters that because of the heat wave, "not only are the fires increasing in intensity but also our Conaf firefighters have greater exposure to dehydration."