Police have launched an investigation following a number of deaths of babies at a hospital.
Cheshire Constabulary has launched the investigation following "a greater number of baby deaths and collapses" at the Countess of Chester Hospital between June 2015 and June 2016.
The probe will focus on the deaths of eight babies but will also review seven further deaths and six non-fatal collapses which happened during the year-long period.
Detective Chief Superintendent Nigel Wenham said: "In May 2017, The Countess of Chester Hospital Foundation Trust contacted Cheshire Constabulary regarding neonatal services at the hospital.
"This was in relation to a greater number of baby deaths and collapses than normally expected during the period of June 2015 and June 2016.
"The hospital also made the constabulary aware of a number of independent reviews that they had commissioned into these deaths.
"As a result, Cheshire Constabulary has launched an investigation, which will focus on the deaths of eight babies that occurred between that period where medical practitioners have expressed concern.
"In addition the investigation will also conduct a review of a further seven baby deaths and six non-fatal collapses during the same period.
"We recognise that this investigation will have a significant impact on all of the families involved, staff and patients at the hospital and the public. Parents of the babies are being updated on the investigation and will be supported throughout the process by specially trained officers. We are committed to carrying out the investigation as quickly as possible.
"The investigation is in its very early stages. We are unable to provide any further details at this time."
A hospital spokeswoman said an independent clinical review into neonatal services had been carried out by the Royal College of Paediatrics and Child Health and the results had been published earlier this year.
The spokeswoman said: "This report pointed to 24 recommendations for improvement, which are now under way.
"It included a further detailed case note review by an independent neonatologist that has been unable to answer all of the questions regarding the cause of death for a number of babies.
"The trust and its doctors have continuing concerns about the unexplained deaths and are very keen to understand that everything possible has been done to help determine the causes of death in our neonatal unit between June 2015 and June 2016.
"As a hospital, we have taken the clinical review as far as we can. We have now asked for the input of Cheshire police to seek assurances that enable us to rule out unnatural causes of death."
Countess of Chester Hospital medical director Ian Harvey said: "We are deeply sorry for the further distress and heartache this will cause. Throughout this, we have never lost sight of the families left bereaved by the loss of their baby and they will continue to be our main concern.
"At every point where the hospital has been able to share information with families and the public, we have done so.
"Approaching the police is not something we have undertaken lightly. This is to ensure we have been completely thorough in understanding what has happened here and to get the answers we and the families so desperately want."
The hospital's neonatal unit, which specialises in babies born early with a low weight or medical condition, cares for an average of 400 babies a year.
In July 2016 admission arrangements were changed and the unit stopped providing intensive care.
Any women expected to deliver earlier than 32 weeks were transferred to a neighbouring facility.
The hospital spokeswoman said since the change to admission arrangements there had been no deaths on the unit.