Authorities in France confiscated 80,000 mobile phones in the country's prisons last year, the justice minister said on Friday.
Gérald Darmanin announced a "zero mobile phones in prison" plan to put an end to prisoners having access to mobile phones, and prevent drugs and other prohibited items from being delivered to inmates by drone.
Under the multi-million-euro scheme, numerous prisons are to be equipped with close-meshed window grilles, X-ray machines and jammers that make it impossible to use mobile phones and disrupt internet connections.
"As I said, 80,000 mobile phones were confiscated last year, as well as drugs," said the justice minister during a visit to La Santé prison in Paris, where former president Nicolas Sarkozy was recently held for three weeks.
"Earlier, prison officers told me that at least two-thirds of the people in La Santé in Paris consume hashish in their cells," Darmanin said.
"The vast majority of French people, as well as prison officers, do not understand how it is possible to make calls on a mobile phone and smoke hashish in prison."
The most dangerous criminals in particular should be cut off from the outside world in high-security prisons, the minister said. He referred to a recent case in Marseille, where a high-ranking drug lord is suspected of having orchestrated a contract killing from prison.
Just a few months ago, French police seized hundreds of mini mobile phones that convicted criminals were using to continue their business from prison.