The move follows the discovery of a number of leads at the materials recycling facility (MRF) in Fourth Drove, Fengate, after the body of the newborn girl was found among household waste yesterday (August 27).

The facility takes in waste from a wide area of the country including Worcestershire and a large section of the rest of the Midlands as well as Peterborough and East Anglia.

Today, West Mercia Police, based in Worcestershire took over investigating the case and detectives are following up a number of leads in the area.

Police also appealed for the mother of the baby to get in touch with officers or medical professionals over concerns about her mental and physical health.

The investigation's move to the West Midlands comes after scenes of crime officers spent much of yesterday sifting through the waste in which the baby was found.

Detective Inspector Jim McCrorie, from Cambridgeshire Police, said obtaining forensic clues had been difficult for scenes-of-crimes officers working in the plant.

He said: "The child has been in that waste material, and that further complicates the investigation."

A post-mortem examination carried out at Addenbrooke's Hospital in Cambridge yesterday proved to be inconclusive, but further tests are due to be carried out.

Det Insp McCrorie said: "There are a number of lines of inquiry.

"We are speaking to staff at the premises and are still carrying out a search."

He added that the grim circumstances surrounding the discovery of the baby made the investigation particularly tough, saying: "It's difficult for all those involved. I think the discovery of a child's body at any time is difficult.

"But we have got to determine the identity of mum and our first step is to put out an appeal to her, because we are worried about her."

Detective Superintendent John Raine, who is leading the investigation for Cambridgeshire police, said: "We are concerned for the mother.

"It may be that she needs some medical attention urgently and we would urge her to go to hospital.

"If she would like to get in touch with us, she can do so on 0845 456 4564 and officers will ensure she gets the information she needs."

A Peterborough GP said today the main concern would be that the child's mother may bleed a lot, which would make her anaemic.

She could also be experiencing stomach pains, an infection, or in some cases the uterus fails to contract and she could need medical attention. But, most of all what she really needs is a friend she can talk to, and who will not judge her.

A council spokesman said today that the facility was likely to remain closed for several days while the investigation continues, but green bin collections in Peterborough would not be affected while the investigation goes ahead.