Abstract: An anti-theft device (2) for a vehicle. The device (2) comprises a valve means (2D) and a control means (2A,2B,2C). The valve-means (2D) is operable to open and close a fuel supply line of a vehicle thereby respectively preventing and permitting fuel flow through said fuel supply line. The valve means (2D) opens in response to an electrical current supply and closes in response to the lack of an electrical current supply. The control means (2A, 2B, 2C) selectively enables and disables said electrical current supply to the valve means (2D). The control means (2A,2B,2C) enables said electrical current supply in response to receiving a specific encoded signal, and disables said electrical current supply at other times.