The customs head office said the plugs -- which were due to be delivered to an importer in the Paris region -- were seized in the northern port city of Le Havre and found to be "dangerous" after analysis.
Among other things, authorities found there was a risk of people electrocuting themselves if they used the plugs.
"Customs services have dealt with nearly 20 cases pertaining to anti-mosquito devices in just a few months," the head office said in a statement.
It is unclear whether all the items came from China, where quality regulations are lax and often unenforced, leading to a string of global safety scares in recent years involving toys, milk and other items.
But the manufacturing powerhouse has also been a victim of safety scares involving foreign products imported into the country.
New Zealand dairy giant Fonterra, for instance, has had to enact a global recall of baby formula distributed in China and other countries, which was tainted with bacteria that can cause botulism, a potentially deadly paralytic illness.
