Police trying to trace the mother of a dead baby boy found at a waste site are appealing to Keighley householders for help.

Thousands of letters seeking public assistance have been sent to areas of the Bradford and Leeds districts, including parts of Keighley, where it is believed the body of the child may have been disposed of with domestic rubbish.

The naked body was found by workers sorting rubbish at Associated Waste Management in Valley Road, Shipley, on September 18 last year.

Police have now studied the routes and pick-up points of domestic refuse wagons and have narrowed down the search area for the baby’s mother.

The letter states: "We are very worried about the mother of the baby and how the baby died.

"We believe the baby may have been born in your area.”

And it asks householders: “Do you know a girl or woman in your area who was pregnant and due to give birth around September 2013?

“Have you seen her recently? Have you seen her baby? Do you have any concerns about this girl or woman?

“Is it possible that the found baby boy could be her child?

“Did you see anybody acting suspiciously who could have deposited the child's body?”

The letter goes on to say police know there are many genuine reasons why pregnancies can come to a sad end and that because of the sensitive nature of the case every effort will be made not to cause any further upset.

Detective Superintendent Mark Ridley, who is leading the investigation, said: "We have identified that waste processed at the site on September 18 last year – the day the baby was found – was collected from areas across north Bradford stretching over to north west Leeds.

"My overriding concern is still the long-term welfare of the baby's mother. While the physical effects may have lessened, we are concerned about the long-term psychological needs of the mother after going through such a terribly traumatic experience."