More than half of hospital consultants admit they have overlooked seriously ill patients and given priority to less urgent cases in an effort to meet government waiting list targets.

In a report on waiting lists released yesterday, the National Audit Office warned that patients in the NHS were often treated not according to clinical priority, but to reduce the number of people waiting. It added, however, that the problem would not be solved by abandoning waiting list targets.

Six hospitals were found to have manipulated waiting lists to cut down on patients waiting longer than six months for treatment. The report also found widespread geographical differences in the time spent waiting for the same treatment in different parts of the country.

The report came as a senior consultant attacked the time patients had to wait. Witek Mintowt-Czyz, a surgeon from south Wales, said it was "inhumane, insane, uncivilised and cruel" and claimed patients waited needlessly, often in pain.

In a survey of 50 NHS trusts carried out before the election, the NAO contacted 550 consultants in three specialties. More than 300 said that to meettargets they treated patients in a different order than according to strict clinical priorities.

Patients wanting a simple operation to reverse a vasectomy, for example, were often treated at the expense of patients needing more complicated surgery for bladder cancer. Often patients with less serious conditions were rushed through as they came close to waiting for 18 months, the maximum waiting time set under the Patient's Charter.

In May, the Government announced it would abandon waiting lists in favour of using the length of time patients waited as the main judge of hospital performance. However the NAO said pressure on waiting times meant clinical priorities would continue to be a problem.

The report said although waiting lists were down and the situation was generally improving, hospital waiting times were still too long and the chances of getting treatment quickly depended too much on where patients live. In Dorset, only 1 per cent of trauma and orthopaedics patients waited more than six months for admission to hospital, compared with over 50 per cent in Croydon, south London.

The NAO called on the NHS to monitor and manage the time patients actually wait more effectively.

Mr Witek-Czyz, from Royal Gwent Hospital, Newport, said patients were forced to wait as operations were regularly cancelled because of a pressure on beds. He spoke out after an elderly patient had waited 32 months for a routine knee operation and had surgery cancelled twice. "Unless you are actually bleeding or ... your life is at risk, then you have got to go on the waiting list and it is huge," Mr Witek-Czyz said.