A senior French health official resigned Monday after the health minister acknowledged that as many as 5,000 people might have died in a blistering heat wave.

Lucien Abenhaim (search), director general of health, said he was leaving his post because of the criticism leveled at the government over its handling of the heat wave earlier this month. He sent his resignation letter to embattled Health Minister Jean-Francois Mattei (search).

Mattei, who also is facing calls for his resignation, said earlier that it is "plausible" that up to 5,000 people could have died but the final death toll would not be known for several weeks.

His ministry has estimated that 1,600 to 3,000 people — mostly elderly — died from heat-related causes starting Aug. 7. Many of the deaths resulted from heat stroke or dehydration, doctors said.

Last week, Patrick Pelloux (search), the head of France's emergency physicians' association and a leading critic of the government's response, said as many as 5,000 people could have died from heat stroke, dehydration and other effects of the withering heat.

Mattei, asked about the assertion on RTL radio, said: "It's a hypothesis — it's plausible — but it's only a hypothesis."

Doctors' groups and the Socialist opposition have taken aim at Prime Minister Jean-Pierre Raffarin's (search) government, saying it did not react quickly enough to the prospect of heat-related deaths.

But lawmakers from the ruling UMP coalition have blamed a law enacted by Socialists when they were in power that limits France's working week to 35 hours. They say the law left medical centers and hospitals short-staffed at the height of the crisis.

The government has said many of the deaths were among elderly people left at home by family members who left on holiday. Much of France shuts down in August.

Earlier this month, parts of France suffered in temperatures of 104 degrees and higher, but temperatures have since cooled to more normal levels.