Documents obtained by The Independent show that patients can be taken out of the system if they fail to respond within 14 days to a letter from their health authority confirming an appointment.
The crackdown, which affects out-patients waiting for non-urgent operations, is aimed at reducing the number of people failing to turn up for hospital bookings.
But the Liberal Democrats claim that the tough new Department of Health (DoH) guidelines will penalise the elderly, vulnerable and anyone on holiday when the letter arrives.
Last week, new figures showed that the number of people waiting for more than 13 weeks for a first out-patient appointment had doubled since Labour took power. From 248,000 in March 1997 to 512,000 in September 1999.
Although the Government is on target to meet its election pledge of cutting in-patient lists by 100,000, the out-patient lists are becoming a political embarrassment. To tackle the rising numbers, NHS Trust managers are acting on DoH guidelines to write to all GPs stating the need to "validate" the lists.
According to the Waiting List Action Team Handbook, published this autumn by the DoH, trust managers should "remove from the booking cycle" anyone who fails to respond to a letter with two weeks. Patients are contacted four weeks before their treatment date and asked to confirm they still want an appointment.
"Patients who confirm are sent an appointment date and time. Patients who fail to confirm are removed from the booking cycle. Alternative patients are then contacted and booked in good time for the clinic," the handbook states.
Oxfordshire Health Authority has already started writing to GPs setting out the new strategy.
The Liberal Democrats, who unearthed the little-known guidelines, claimed that they meant that patients were being struck off the waiting lists without their knowledge, consent or having been seen by their GP.
Nick Harvey, the party's health spokesman, said: "This sinister bureaucratic ploy to write to half a million people in a calculated attempt to knock them off waiting lists is diverting much needed resources from the NHS," he said.
"The referral by a GP in consultation with the patient is the cornerstone of our NHS. To penalise sick people for not replying to confirmation letters is an unacceptable interference in the doctor-patient relationship.
"The elderly and illiterate are particularly vulnerable. Even people on holiday could fall victim to the Government's dangerous strategy."
Approximately 11 per cent of people fail to keep their first hospital appointment.Reuse content