Surveillance cameras deployed at industrial plants, prisons, banks and the military can be hacked and could be used to spy on facilities or gather sensitive computer networks, according to a US security expert.

Reuters reported citing National Security Administration’s former software developer, Craig Heffner, that there were unreported bugs in digital video surveillance equipment from firms, including Cisco Systems, D-Link and TRENDnet.

"It’s a significant threat," Heffner said.

"Somebody could potentially access a camera and view it. Or they could also use it as a pivot point, an initial foothold, to get into the network and start attacking internal systems."

Heffner also reported that there were hundreds of thousands of surveillance cameras that could be accessed through the public Internet.

The US security expert will demonstrate techniques for exploiting the discovered bugs at the upcoming Black Hat hacking conference starting July 31, 2013, in Las Vegas.

The vendors are also planning top implement appropriate action required to protect their equipment following Heffner’s presentation at Black Hat.

The conference will also involve other talks that will explore threats to Microsoft Windows and Apple systems, mobile phone networks, medical devices and systems deployed to control industrial plants.