Police were called to the baby section of South Bristol Crematorium and Cemetery in Bridgwater Road, Bedminster Down, Bristol early on Sunday afternoon.

They found toys and tributes left by grieving relatives had been smashed, and flowers strewn around.

Several of the graves belonged to children who died after heart surgery at the Bristol Royal Infirmary.

However, parents have accepted the attack was almost certainly a tragic coincidence.

A spokesman for Avon and Somerset Police said: "We were called at 1pm and found around 150 graves had been damaged.

"We have a large number of distressed parents to deal with and are now investigating the incident."

Mementoes damaged

Police said the vandalism took place overnight and damage was to ornamental pots, flowers and mementoes from families which were broken and strewn around the cemetery.

They said most of the headstones were undisturbed and they were now waiting to study CCTV camera footage of the incident.

They are looking for two teenage boys seen cycling in the cemetary on Saturday night, shortly before the attack.

Bristol City Council, which runs the cemetery, said the cemetery had been kept secure and locked at night.

A spokeswoman said: "The council is working with the police to investigate this terrible crime."

Anyone with information should call Crimestoppers on 0800 555 111 or their local police station.