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 the unidentified arsonists blamed for dozens of fires that have ravaged southern France this summer.

The dead firemen were burned alive Monday night after their truck became encircled by flames. Three others managed to escape from a second truck that was also trapped by the fire.

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 people died in fires in July.

A fleet of 25 water-dropping planes were deployed to help firefighters put out the blaze 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 that southern France has seen for a quarter of a century.

The dead firefighters -- aged 37, 42 and 43 -- were all married and had a total of seven children. Colleagues from their brigade were relieved from duty and were receiving psychological counselling on Tuesday.

President Chirac on Tuesday visited the firefighters' central command in the town of La Garde-Freinet, close to Saint-Tropez, where he promised that the government would "make an extra effort" to boost resources and equipment for dealing with wildfires.

He also voiced "deep sadness" over the three latest 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".

Local prosecutor Christian Girard meanwhile 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 honour 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 holiday 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-dropping 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.

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