France has suspended hunting in the western Pyrenees mountains to save a bear cub orphaned when its mother was killed by hunters on Monday.
Only about 15 brown bears are thought to remain in the Pyrenees
The last female bear native to the region was surprised in the Aspe valley with her 10-month-old cub, who fled.
The six hunters claimed they acted in self defence, but environmentalists say the group deliberately visited an area known to be occupied by bears.
President Jacques Chirac said the death was a "great loss for biodiversity".
Serge Lepeltier, France's minister of ecology and sustainable development, is to travel to the area on Thursday.
An investigation has been opened to determine any criminal liability, French news agency AFP said.
Last female bear
Hunting and dog walking would be banned temporarily in the
districts where the cub is believed to be roaming, a government representative in the south-western region said.
The hunters claim they fired in self defence after the 15-year-old bear - known by game wardens as Cannelle - charged their dogs and bit one of them.
Cannelle - or Cinnamon in English - was one of only 15 brown bears believed to remain in the Pyrenees, on the border between France and Spain.
Officials say the cub has a reasonable chance of survival if it is not disturbed, given its age and the abundance of food.
The anger of environmentalists is all the greater because Cannelle was the last female bear in the region of pure Pyrenean stock.
While two other males are indigenous, the remainder are bears imported from Slovenia. Only three or four breeding females now remain in the whole mountain range.
Attempts to increase the number of bears - a protected species - by bringing in animals from other areas of Europe have been opposed by cattle and sheep farmers.