Doctors' negotiators are preparing to demand extra controls on the new NHS-wide number-tracing service.

The NHS strategic tracing service has already gone out to tender after a very short consultation period, ending in June .

The British Medical Association's general medical services committee believes the tracing service will act as a virtual national database of all individuals, accessible to hundreds of thousands of NHS administrative staff with no professional supervision.

Its adviser, medical security expert Ross Anderson, warned: 'We will see one or two murders a year and several hundred cases of illicit serious assault and stalking, due to people being found through it.'