German news weekly Der Spiegel reports that the US National Security Agency can access users' data on all major smartphones.
The magazine cites internal documents from the NSA and its British counterpart GCHQ in which the agencies describe setting up dedicated teams to crack protective measures on iPhones, BlackBerry and Android devices.
This data includes contacts, call lists, SMS traffic, notes and location data.
Der Spiegel says the documents don't indicate that the NSA is conducting mass surveillance of phone users but rather that these techniques are used to eavesdrop on specific individuals.
The article published Sunday doesn't say how the magazine obtained the documents. But one of its authors is Laura Poitras, an American filmmaker with close contacts to NSA leaker Edward Snowden.