Two prominent law enforcers in the U.S. who have been pushing Apple to do more to combat iPhone theft say they appreciate a new feature previewed earlier Monday that could help make stolen iPhones more difficult for thieves to resell.

The "activation lock" feature, which was shown at the company's Worldwide Developers Conference in San Francisco on Monday, requires the use of the owner's Apple ID and password to reset or reactivate a phone that has been locked, disabled or wiped.

"We are appreciative of the gesture made by Apple to address smartphone theft," said George Gascón, the district attorney for San Francisco, and Eric Schneiderman, state attorney general for New York, in a joint statement.

"We reserve judgment on the activation lock feature until we can understand its actual functionality," they said.

The two have been critical of Apple, other leading smartphone makers and cellular carriers for what they see is a lazy response to the rising number of smartphone thefts in major American cities. In several cities, smartphone thefts now account for more than 40 percent of street crime, and a sizable chunk of those involve robbery with a gun or a knife.

While many phones offer a remote lock or remote wipe feature to safeguard customer data if stolen, there isn't generally a reliable way to render a phone inoperable so that it can't be reset, reformatted and resold. The majority of street thefts appear aimed at resale of the handsets rather than theft of personal data on a phone.

"We are hopeful that the cell phone industry will imbed persistent technology that is free to consumers that will make a phone inoperable once stolen, even if the device is off, the SIM card is removed or the phone is modified by a thief to avoid detection," the two officials said.

Apple's announcement comes just a few days before representatives of major smartphone players are due to meet with Gascón and Schneiderman in New York.

The New York state attorney general wrote to Apple, Microsoft, Google and Samsung in mid-May asking them to meet with him. In the letters, he alluded to possible prosecution under two parts of state law that deal with deceptive trade practices.

Martyn Williams covers mobile telecoms, Silicon Valley and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is [email protected]

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