Chirac told a memorial ceremony here in the Maures hills, northwest of the fashionable Riviera resort of Saint-Tropez, that he would call for "the utmost severity" in dealing with fire-starters, unidentified but blamed for dozens of fires that have ravaged southern France this summer.

The dead firemen were burned alive Monday night in their truck when it was suddenly encircled by flames. Three other firemen in a second truck that was also trapped in the flames managed to escape.

Meanwhile, the ranks of firefighters swelled to some 2,000 as hundreds of reinforcements were sent to battle a nearby brush fire, which was progressing at a slow but steady pace through the Maures hills, where four died in fires in July.

A fleet of 25 water-dropping aircraft were deployed to help firefighters put out the blaze, previously split on two fronts but now just a solid wall of fire burning near the town of Cogolin, west of the Riviera resort of Saint-Tropez.

Emergency workers said their task was made a bit easier when the swirling Mistral winds tapered off to about 20 kilometers (12 miles) an hour, as opposed to 50 kilometers an hour on Monday, when the three firemen were killed.

Some 4,500 hectares (11,000 acres) have thus far been consumed by the latest blazes in the Maures hills, which has suffered from a scorching heat wave and the worst drought in southern France in a quarter of a century.

The dead firefighters -- aged 37, 42 and 43 -- were all married and had seven children among them, aged one to 12. The rest of their brigade was removed from duty and was receiving psychological counseling.

Chirac expressed "deep sadness" over the deaths, hailing the courage of the "thousands of volunteers and professionals who have fought day and night for the last three months against the fires devastating the south of France and Corsica -- too many of them started deliberately".

Public prosecutor in the southern city of Draguignan Christian Girard, said an investigation had been launched into the origins of the Maures fire and called on locals to provide information.

"If there are pyromaniacs, we have to neutralize them and end all this," he said while visiting a makeshift chapel built in honor of the dead firefighters.

Since Sunday, about a dozen other firefighters have suffered burns or other injuries fighting the fierce flames.

Rescue workers have evacuated 40 families from the town of La Garde-Freinet, as well as several campsites and a vacation resort in the Maures hills.

Three helicopters and a boat were standing ready to evacuate firemen and civilians, and a team of psychologists were on hand to help trauma victims, officials said.

Regional authorities announced that the resumption of classes following the summer break had been postponed in seven towns around the Gulf of Saint-Tropez.

Public prosecutors said they had launched a preliminary inquiry to determine the cause of the fire.

Wildfires also continued to blaze out of control Tuesday in Corsica, authorities said, with Cap Corse, the northernmost tip of the French Mediterranean island, the most at risk.

Some 800 firefighters backed by nine water-carrying aircraft struggled to rein in the fires on the island, with officials saying they were on the verge of bringing them under control.

One person died in July in Corsica's fires, bringing the death toll from France's summer fires to eight.

French Interior Minister Nicolas Sarkozy, during a visit to fire-hit areas in southern France on Monday, said a total of 54,000 hectares of woodlands had been destroyed across the country thus far this year -- the worst total in 15 years.

TERRA.WIRE