Elsewhere, lightning struck an electrical center in Switzerland, blocking about 100 trains in the second major breakdown to hit the Swiss railway system in two days.

The Paris fire department said it had received about 500 calls because of flooded basements, fallen trees and short circuits.

In the surrounding Essone and Yvelines regions, firemen were called out on hundreds of other emergencies.

In the old royal court city of Versailles, firemen attended about 300 emergency calls.

No casualties were reported, but a motorcyclist had to be resuced when he was engulfed by water under a Paris road tunnel.

Officials at Charles de Gaulle and Orly airports said all flights had to be suspended for more than hour, but they said the situation returned to normal later in the evening.

Determined to prevent a repetition of a heatwave disaster two years ago in which thousands of elderly people died, Health Minister Xavier Bertrand, said he would announce improvements in a nationwide emergency system next week, including a requirement that all establishments for the elderly should be provided with at least one air-conditioned room.

He also said his ministry would publish an additional six million copies of a leaflet telling elderly people how to avoid become heatwave victims. Three million copies of the document have already been distributed.

Heatwave protection was stepped up to the third of four levels in three eastern regions of France, putting hospitals on alert and requiring social workers to make contact with members of the public at risk from heat-stroke.

An estimated 30,000 people died in Europe during the 2003 heatwave, when temperatures rose above 40 degrees Celsius (104 F) during the day and remained high during the evenings, with 14,847 deaths in France, the majority elderly, between the August 4 and 18.

There was a subsequent public outcry about the government's slow response to the disaster.