A technology firm in the US state of California has unveiled a prototype of a camera-equipped micro aircraft that looks like a hummingbird.

The Nano Hummingbird was developed by AeroVironment for the US Defence Advanced Research Projects Agency (Darpa) and may one day be used for rescue and surveillance missions for the military.

The prototype uses its wings to achieve propulsion and maintain balance, and it is equipped with a small camera that can stream live video.