The interior ministry declared a state of alert in 23 departments, including Paris, triggering stepped-up efforts to locate homeless people and take them into shelter.

Temperatures are predicted to fall to below minus 10 degrees Celsius (14 degrees Fahrenheit) in parts of northern France Sunday night, with the freeze spreading southwards. However a thaw is due mid-week.

Meanwhile technicians were working to reconnect around 9,000 homes that remained without electricity Sunday after the freak storm that swept across northern France on Friday, killing six people.