Temperatures in some parts of France will reach 40 degrees Celsius (104 degrees Fahrenheit) this weekend, forecasters predicted Thursday, triggering an alert system set up after 15,000 people died in a heatwave in 2003.

Health Minister Marisol Touraine said a level 2 alert on the 1-3 heatwave warning system would be issued to ensure the public was aware of the need to ensure the well-being of the elderly, babies and other people particularly vulnerable to unusually high temperatures.

"We have to be careful not to cause panic but at the same time make sure everyone is taking sensible precautions," the minister said.

State forecasting body Meteo France expects temperatures to reach 40 degrees in south-western and central France with figures in the high 30s in much of the rest of the country.

France introduced its heatwave warning system in 2004, a year after 15,000 mostly elderly people died in an unexpected and sustained spell of unusually hot weather.