Critics say the caravan park should not have been built near the sea wall
Blame is being laid on weak and aged sea defences after violent storms left at least 50 dead and thousands homeless along France's Atlantic coast.
Many died after the sea wall off the coastal town of L'Aiguillon-sur-Mer was breached, allowing 8m-high (26ft) waves to crash through the streets.
A local governor said the walls dated back to the time of Napoleon and needed to be replaced with taller barriers.
President Nicolas Sarkozy has pledged 3m euros (£2.6m) in emergency aid.
He was touring the worst-affected western coastal regions of Vendee and Charente-Maritime after declaring a national disaster, and promised to channel recovery funds quickly.
"It is a national disaster, a human drama with a terrible death toll," he said. "The urgent thing is to support the families who have members missing or dead."
The Atlantic storm, named Xynthia, smashed into the western coasts of France, Portugal and Spain on Sunday, with torrential rain driven by winds of up to 140km/h (87mph).
The storm has since swept north-eastwards into Germany, Belgium and the Netherlands. and deaths have been reported in Portugal, Spain, Belgium and Germany.
While many L'Aiguillon-sur-Mer residents were trying to be stoical about the situation, there is some anger in the town that not enough had been done to maintain its sea defences, says the BBC's Emma Jane Kirby in the town.
Poor planning was also being blamed for constructing a mobile home park so close to the old sea wall.
Aftermath of storms that have hit western Europe
"The sea wall that broke dated from (the era) of Napoleon," said Philippe de Villiers, a former presidential candidate who heads Vendee's regional government.
"Either we build (new) sea walls, in which case they need to be taller and taller... or we have to build further inland," he told France-Info.
But the French President said it was too early to start criticising the sea walls for the high death toll.
French Prime Minister Francois Fillon said flood prevention dykes would be strengthened.
"The priority now is to make all the homeless people safe, all the people who are still threatened by the rising waters," he said.
Nearly 10,000 emergency staff were working on the west coast on Monday morning, searching for and helping survivors.
As many as nine people are thought to be missing.
Massive power outage
In France, Xynthia put five of the country's 95 departments on red alert - only the second such warning since a new emergency system was introduced in 2001.
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