The 33-year-old former nurse was sentenced to a whole life order after she was convicted of the murders of the babies and the attempted murders of six others at the hospital's neonatal unit in 2015 and 2016.

Detective Superintendent Simon Blackwell, who is strategic lead for Operation Hummingbird, which investigated the allegations against Letby, said: "Following the lengthy trial, subsequent conviction of Lucy Letby and an assessment by senior investigative officers, I can confirm that Cheshire Constabulary is carrying out an investigation into corporate manslaughter at the Countess of Chester Hospital.

"The investigation will focus on the indictment period of the charges for Lucy Letby, from June 2015 to June 2016, and consider areas including senior leadership and decision making to determine whether any criminality has taken place.

"At this stage we are not investigating any individuals in relation to gross negligence manslaughter."

He added: "The investigation is in the very early stages and we are unable to go into any further details or answer specific questions at this time.

"We recognise that this investigation will have a significant impact on a number of different stakeholders including the families in this case and we are continuing to work alongside and support them during this process.

"You will be notified of any further updates in due course."

Jane Tomkinson OBE, the acting chief executive officer at the Countess of Chester Hospital NHS Foundation Trust, said in a statement after the police announcement: "We were deeply saddened and appalled at Lucy Letby's crimes when the verdicts were delivered.

"Following the trial we have always maintained we will be supporting the ongoing investigation by Cheshire Police and will be cooperating fully with the investigation announced today so that we can help get the answers that the families and babies affected by this case rightly deserve.

"Cheshire Police have given us their assurance that they are providing ongoing support to the families, who remain at the forefront of our thoughts and efforts to support this investigation.

"It would not be appropriate for the Trust to make any further comment at this time."