New York City mayoral front runner Bill de Blasio and state Attorney General Eric Schneiderman are calling for smartphone manufacturers to improve security on their devices.

De Blasio, the public advocate, said Monday he wrote a letter urging that Apple, Google/Motorola, Samsung and Microsoft install a “kill switch” on their phones.

That mechanism would allow the phone’s owner to permanently disable the device if it’s stolen. That way, the phone would become useless, taking away its value to a would-be thief.

Approximately 20% of all thefts in New York City are of smartphones. Nationally, smartphones make up one-third of all items stolen.

Elected officials in San Francisco and London have also joined the call to improve cellphone security.

De Blasio faces Republican Joe Lhota in the Nov. 5 general election.

(AP)