The excuse, particularly among juniors, is that they are pushed for time

Dr Ben Swift, researcher

It could not only prove misleading for relatives, but could harm future research if a precise cause of death is not recorded, they added.

The researchers from the Department of Histopathology at Leicester Royal Infirmary looked at 1,000 records covering a period between October 1999 to June 2000.

They found that only 55% were completed adequately.

No improvement

The results have not improved from surveys in recent years - despite the introduction of death certificate training at medical schools.

Lead researcher Dr Ben Swift said: "A lot of doctors don't appear to understand the importance of the death certificate.

"The excuse, particularly among juniors, is that they are pushed for time, which I can sympathise with, having been a junior doctor.

"But they have to remember that this is still a legal document and needs to be completed with care."

A typical mistake, he said, might involve simply saying that a patient died of lung cancer, when in fact there are many different types of lung cancer.

Researchers need to know exactly which one the patient died from in order to carry out future research projects.

In the case of a stroke, doctors should write down, if possible, where in the brain the stroke occurred, and what type of stroke it was.

Some doctors even use abbreviations in their certificates.

Investigation

If staff at the register of births, marriages and deaths are unhappy with the condition of a death certificate, they can refer the matter to the coroner for investigation - in these circumstances, the doctor could be in trouble.

There is now the possibility that the Home Office will introduce new rules restricting who can fill in a death certificate.

This comes in the wake of the Harold Shipman court case, which has prompted a review of the system.

Dr Shipman, a former GP from Hyde in Cheshire, killed dozens of patients then falsified their death certificates.