A raid last Friday in the city of Annecy netted a tonne of hunting ammunition and 300 kilogrammes of ammunition for military weapons, as well as nine pistols, the judicial police said.

Police also found material that could be reassembled to produce thousands of firearms in garages in an industrial zone, the judicial police said.

Officers carried out the raids after detaining and questioning a man in his twenties who is suspected of trafficking in weapons.

The suspect had been staying with a couple "who knew of the arms trafficking but had not been involved in it," police commissioner Guillaume Fauconnier told AFP.

The weapons stockpiles were found in garages next to a home occupied by squatters.

It belongs to a former gunsmith, currently in the hospital, who is a World War II enthusiast.