Edward Snowden and Andrew “Bunnie” Huang have co-created a phone case that will alert smartphone owner when the phone data is being monitored, a report published by The Guardian said on Friday.

The former Central Intelligence Agency employee, who whistle-blew top-secret NSA documents leading to revelations about US surveillance on phone and internet communications, presented the product via a video link to event at the MIT Media Lab in Cambridge, Massachusetts.

The “introspection engine” makes the smartphone owner aware when the information is being obtained by governments from his device over cellular, Wi-Fi or Bluetooth connections.

The case will act as a “kill switch” which will switch off the phone's power supply when any attempt to data transfer is detected.

“If you have a phone in your pocket that’s turned on, a long-lived record of your movements has been created,” Snowden said.

“As a result of the way the cell network functions your device is constantly shouting into the air by means of radio signals a unique identity that validates you to the phone company.

“And this unique identity is not only saved by that phone company, but it can also be observed as it travels over the air by independent, even more dangerous third parties.”

The duo made the audience aware that their phones can be traced even in the ‘airplane mode’.

“Trusting a phone that has been hacked to go into airplane mode is like trusting a drunk person to judge if they are sober enough to drive.”

“Introspection engine” is a part of Snowden's series of attempts to inform general public about the surveillance capabilities available with governments around the world and to protect their data.