Doctors came under fire yesterday over new rules governing the retention of organs from dead patients.

In the wake of the disclosures last year that thousands of organs had been removed from dead children withoutparental consent, guidelines have been drawn up by the Royal College of Pathologists. The new rules say much greater care must be taken in obtaining consent from relatives, but parents complained they were not tough enough.

The rules were published yesterday in advance of inquiries at Alder Hey Children's Hospital in Liverpool and the Bristol Royal Infirmary, which are investigating how children's organs came to be removed and kept at the hospitals without parents' knowledge.Both inquiries are expected to report in the next few weeks.

The college says relatives must always be told what has been taken and why, and greater efforts made to ensure they understand medical terms. In the past relatives have been confused about the difference between tissue samples (small portions of organs) and whole organs and the college says this must be clarified.

Where a post-mortem examination is required by law (in which the pathologist is obliged to retain anything which has a bearing on the cause of death) the guidelines say the relatives must be told what has been retained and its purpose.

Professor John Lilleyman, president of the Royal College of Pathologists, said: "In the past it was not usual to describe details of post-mortems. The reason was simply a natural desire to avoid adding to the distress of bereaved relatives. It is now clear this is no longer appropriate and in future everything will be fully explained."

Yesterday parents of children who had died at Alder Hey criticised the guidelines on the grounds that they were voluntary. Ed Bradley whose daughter's heart, brain and lungs were removed, said: "Up until yesterday, there were already guidelines in place. However, it is tragically obvious that [they] were ignored in the past. I welcome the recommendations but they are worthless unless they are made mandatory."

Ministers are likely to come under pressure to enshrine the measures in law. Professor Ian Kennedy, the chairman of the inquiry into the deaths of baby heart surgery patients in Bristol, which is also looking into the matter of organ removal, is on record as saying legal changes are "probably required".

Yesterday, the Health minister Lord Hunt of Kings Heath, said the management of Alder Hey's pathology service would be tightened up. The announcement followed a report into the case of 10-day-old Stephen White, whose organs were disposed of. The case led to last week's sacking of Frank Taylor, the chairman of the Royal Liverpool Children's Trust, which includes Alder Hey.

Retaining organs is critical for the advance of medicine and doctors fear that if there is a public backlash, medical progress could be impeded.