Some private crematorium operators do not routinely return ashes left behind after the cremation of babies to bereaved parents, one of Britain's biggest owners said.

The Co-operative, whose crematoriums include Craigton in Glasgow, said the remains were considered "coffin ash" and it did not return human remains if there was no visible bone matter.

It added that parents would then be informed if there were no remains.

A spokeswoman said: "Ashes are returned to families if they have requested them and as long as there are cremated remains to return." She added that coffin ashes were scattered in a garden as "a mark of respect".

The Co-op said it followed the rules of the Federation of Burial and Cremation Authorities, which distinguishes between ashes and cremated remains.

Dignity, the largest provider of funeral services in Britain, which runs crematoriums in Dundee, Irvine, Moray and Holytown in Lanarkshire, said that depending on the age and physical development of a baby, "there may be times when there are no ashes. If there are no ashes, we always inform the family's funeral director".

Some council-run crematoriums, including Mortonhall in Edinburgh, which is at the centre of the ashes scandal, face legal action because parents had been told there were no remains, only to find out that ashes had been buried without their knowledge.