Forensic experts have been examining the scene

The naked child was discovered by a householder in his back garden in Railway Street, Splott, on Saturday.

It is believed that the boy was born full-term, but it is not yet known whether he was stillborn.

Police are appealing for the mother to come forward. They believe she could be as young as 13.

Forensic tests have been carried out and a post-mortem examination on the boy's body was being held on Monday. Officers have carried out house-to-house inquiries and have set up an incident room.

A team of around 20 officers are working on the investigation. They have turned their attention to visiting schools in the area and health centres in a bid to track down the mother.

Detective Inspector Andy Davies of South Wales Police said:"No-one has really been able to give us the answers we're looking for to trace the mother.

"So we're now thinking that there is a good chance that the mother is young in age - probably as young as 13 or 14 years of age, and has concealed the whole pregnancy from friends and family.

Householder Roger Biggs said he was very distressed at the discovery

Officers would also like to hear from anyone who knews of an expectant mother who should be full-term about now, and appeared to be in distress.

"If the mother hears this appeal, then we urge her to contact us immediately to ensure her well-being," he added.

Mal Davies, the headteacher of Willows School in the Splott area of Cardiff said they were concerned that the mother could be a young teenager.

"Because of the vulnerability of young people we are inclined to believe or suspect that it is a young person in a desperate situation," he said.

Householder Roger Biggs, who discovered the body in his back garden, said it had distressed him.

And local councillor Alexandrina Evans said other neighbours had been shocked.

"This is a very close-knit community," Ms Evans said. "Nearly everybody knows everyone else, and they all look out for one another so they will be totally devastated by this.

"I feel very sorry for the mother - she must be in a terrible state of shock and doesn't know who to turn to and where to go. I really feel for both parties."