All cases of cot death should be investigated by police and doctors, researchers behind a major study into Sudden Infant Death Syndrome have said.

Such visits should be carried out 24-48 hours after the sudden and unexplained death of an infant by a health professional and a specially trained police officer, the Foundation for the Study of Infant Deaths (FSID) have now recommend.

And they say that far from adding to parents' feelings of culpability and grief, the bereaved ought to be given the opportunity to talk about the circumstances surrounding their baby's death.

The report, funded by the Confidential Enquiry into Stillbirths and Deaths in Infancy (CESDI), the FSID and the Department of Health, indicated that 6% of cot deaths are probably the result of maltreatment.

But FSID spokeswoman Sarah Kenyon said: "These visits first and foremost would allow us to gather the information we need to keep parents informed of best practice.

"At the moment there is no systematic way of collating this information and it is vital that we develop one."

On the FSID website, chairman Colin Baker outlines how when his baby son Jack died, no-one asked any questions.

He says he wishes information had been taken after Jack died, so that the reasons for his death might have been discovered.

He goes on: "Nobody asked anything, really, about the circumstances - how much he had eaten the day before, the temperature in his room, whether there had been any change in routine.

"Looking back, my wife Marion and I realise that, had more questions been asked, we might have learned more about our son's death - information that might possibly have helped prevent other babies' deaths."

Cherry Chapel, of CESDI, says that the police officer who makes the visit to the home of the dead infant should ideally be from the Child Protection Unit, and who would therefore have experience of dealing in such matters.

She said: "This is not about apportioning blame. What the research found was that in 60% of the parents of babies who had died, the message about reducing the risk from SIDS had not got through.

"If we can get that message across with the help of health visitors and the media, we can hopefully reduce the number of deaths."

Ms Kenyon said that questions such as did the parents smoke, what the infant had eaten, and what the room temperature had been, would be asked sensitively.

She said CID would only be involved if a coroner thought they ought to be involved. In the UK, all cot death cases require a post mortem.

She said: "Another measure we would like to see introduced is for the post mortem examination to be carried out by a paediatric pathologist - someone who knows how babies work and what might be responsible for their deaths.

"We would also like to see a case study review after each death, involving the members of all the agencies involved."

Ms Chapel added that cot death was not a diagnosis in itself, but was a conclusion reached when no other reasons could be found for an infant's sudden death.

Mr Baker said that the cost of introducing the system would be hundreds of thousands, rather than millions, and would probably save the lives of many babies.

He said: "If CJD took a life every single day there would be uproar. Cot death takes a life every single day, and we want the best possible effort made to understand why cot death is still the main cause of death in infancy."