Babies' ashes were likely to have been mixed with those of the next adult to be cremated the following morning at Mortonhall, according to Dame Elish Angiolini's report into the scandal.
Dame Elish's inquiry report yesterday spoke of an apparent belief at the Edinburgh crematorium that the bones of foetuses and stillborn and neonatal babies could not survive the cremation process, despite available information to the contrary.
The former Lord Advocate concluded the situation at Mortonhall stemmed from a failure to adapt to changes in society in recent years and that there was a lack of proper guidance and monitoring on the issue.
The inquiry found:
l Overwhelming evidence foetal bones do survive cremation, at least from 17 weeks gestation.
l A "long-standing and wholesale" failure to keep accurate records of the cremation of stillborn and neonatal babies.
l The council should take urgent steps to change its forms so there is a "bold explanation" of what will happen to the deceased's remains.
l Staff should be properly trained in dealing with parents "in a state of profound shock and grief".
l The method of cremation of infants should be reviewed.
Dame Elish said in her wide-ranging 600-page report the crematorium did not address how society's attitude had recently developed over bereavement.
She said: "The extent to which practices in the cremation of foetuses, stillborn and neonatal babies at the Mortonhall Crematorium have failed to reflect the changes over the years in social attitudes and the corresponding need for greater care, sensitivity and transparency is partly a product of an inward-looking and isolated managerial approach at the operational level.
"That situation was allowed to persist because of an absence of meaningful supervision or leadership from senior management on this matter.
"Staff employed there for many years largely adopted practices and beliefs formed and fixed over several decades."
She added: "They worked for many years under the direction and supervision of the same superintendent, who also preserved such opinions.
"She was a manager with a lively concern for efficiency and cleanliness but an apparent aversion to change."
The report said staff told the investigation they had discussed the possibility of getting a baby cremator at the site but were told by the council it was not financially viable, although there is no record of those discussions.
The report continued: "The apparent belief at Mortonhall that the bones of foetuses and even stillborn and neonatal babies could not survive the cremation process continued, despite the exposure of the superintendent and other staff to evidence and information to the contrary."
It is "likely" some of the ashes of some babies will have been mixed in with the next adult to be cremated the following morning or interred in the land adjacent to the garden of remembrance, the report said.
The report also addressed the issue of the equipment used in cremations.
It said that, ideally, the cremation process "should destroy combustible organic components of the body and retain inorganic parts".
The usual conditions for cremation of adults are not suitable for infant cremations.
The essential characteristic of infant cremation must be a gentle process, the report said.
There has been little attention paid by the industry to how full-size cremators operate with infant cremations and if there are to be consistent successful infant cremations - with recoverable remains - changes are necessary, Dame Elish said.
The report continued: "The outcome of this investigation will cause more pain and distress for most of the parents of the 253 babies who are the subject of this investigation.
"It cannot be said with any certainty what remains of which babies are interred in the garden of remembrance (at Mortonhall)."
It added: "The great tragedy of these events over many years is many parents will now be left with a lifetime of uncertainty about their baby's final resting place."
The crematorium was considered by the council as a model of excellence, but "the reality was very different so far as it related to the cremation of foetuses, stillborn and neonatal babies", the report said.
Parents were led to believe there would be nothing to scatter and the ashes were dumped in a mass grave in a so-called garden of remembrance at the crematorium.
The land at the garden is now to be examined under the recommendations.