The study found poorly-treated ischaemic heart disease - such as angina - was responsible for most of the avoidable deaths (250,000) followed by cardiovascular disease (80,000).

Mismanaged, late diagnosed or mistreated colon and rectal cancer claimed 28,000 lives, while inadequately treated cases of pneumonia claimed 25,500.

The study also showed that while there had been a general decline in avoidable deaths, the number of fatalities due to septicaemia and medical and surgical "misadventures" rose.

The research was headed by Professor Alastair Leyland, of the Medical Research Council's social and public health sciences unit at Glasgow University.

Another study in April by Dr David Kingsmore, a consultant general surgeon at Glasgow's Gartnavel Hospital, found that across Scotland up to 1000 patients a year were being killed as a result of basic error by doctors and nurses.

And an internal NHS report commissioned by Dr Harry Burns, Scotland's chief medical officer, shows the country has one of the highest avoidable death rates in Europe.

Despite Scotland spending more per person on healthcare than any other European nation, only Portugal comes close in the avoidable deaths "league of shame".

The deaths have been blamed on a series of failings, including GPs not recognising symptoms early enough, unacceptable delays for treatment, poor access to drugs and bungled operations.

Campaigners called for an urgent investigation into the situation.

Margaret Davidson, chief executive of the Scotland Patients' Association, said: "It's getting to the stage where people are going to be scared of going into hospital.

"Where has all the money that's supposedly been ploughed into the NHS actually gone?"

A spokeswoman for NHS Greater Glasgow and Clyde said: "We have not yet received a copy of this report.

"However, when a copy is made available to us, our Director of Public Health and Medical Director will study in detail the report's findings."