Professor Michael Green wrote in the British Medical Journal that pathologists should adopt a "think dirty" approach.

However, the Foundation for the Study of Infant Deaths (FSID), a cot-death charity, has condemned Professor Green's standpoint.

The Reverend Ron Robinson, a FSID trustee, said: "The sudden death of a baby is one of the most devastating things that can happen to a family.

"It is manifestly unfair to exacerbate their pain by casting general aspersions of guilty that they are all presumed to have murdered their child, for that is what 'think dirty' means.

"What we need are open-minded, objective professionals, who come to a conclusion only after all avenues have been examined. Instead of think dirty, think fair."

High levels of misdiagnosis

FSID acknowledged that a small proportion of deaths diagnosed as cot death are actually due to unnatural causes.

But Professor Green estimates that the level of misdiagnosis may be as high as 40%.

He writes in the BMJ: "If we assume that the numbers of adults who harm their children have remained fairly constant over the years, then in the relatively low number of baby deaths currently occurring, the proportion of suspicious cases is increased accordingly.

"It follows that all of us involved in such deaths should approach them with suspicion, albeit cautiously expressed.

"The advice given in a recent Canadian investigative protocol to think dirty although a little graphically phrased for my liking, sums it up."

Professor Green, however, warned against adopting a witch-hunt mentality.

He said: "I am fully aware of the distress that such an approach may cause to recently bereaved and totally innocent parents.

"I am also old enough to recall the bad old days of the 1960s, when deaths were wrongly attributed to unsuitable bedding or inappropriate care, leading to unnecessary inquests and pillorying of the parents in the local press."