The VeriChip is a glass encapsulated RFID tag that is injected into the triceps area of the arm to uniquely identify individuals. The tag can be read by radio waves from a few inches away.

The news was reported by CASPIAN (Consumers Against Supermarket Privacy Invasion and Numbering), a US organisation that opposes the use of surveillance RFID cards.

Although CityWatcher does not require its employees to take an implant to keep their jobs, they won't get in the data centre without it. CASPIAN’s Katherine Albrecht says chipping sets an unsettling precedent. "It's wrong to link a person's paycheck with getting an implant,” she says.

CityWatcher argues that chipping employees is a move to increase the layer of security, as present systems can be compromised. However, CASPIAN warns that this can happen to implantable chips too. Security researcher Jonathan Westhues - author of a chapter in a book titled Hacking the Prox Card - recently demonstrated how the VeriChip can be skimmed and cloned by a hacker. A cloned chip theoretically could duplicate an individual's VeriChip implant to access a secure area.