Nokia has applied for a US patent covering a mobile phone capable of sending a covert emergency message, complete with pictures, sound and location.

The company applied for design protection last year but remains tight-lipped about it. "The patent application doesn't mean that we're necessarily planning to install this emergency feature in any of our phones in the future," said a spokesman. "We're constantly developing new technologies in our research labs and applying for patents to protect our intellectual property rights."

One design would see two buttons, one on each side of the handset. By pressing the buttons simultaneously for a pre-determined amount of time, users would speed-dial an emergency number and begin recording and sending sounds and snapshots or even video clips to a trusted centre. If equipped with GPS, it would also provide location information.

Should transmission be temporarily lost, the phone stores images and video in its memory and automatically transmits this data once a signal is picked up. Transmission can be discreet to prevent an abductor from knowing that an emergency message has been sent.

Once users initiate an emergency call, they can only halt it by entering a personal code.

The patent application can be viewed on the US Patent & Trademark Office website here.