The “emerging serious concern” of a rise in baby deaths at the Countess of Chester Hospital should have been shared openly, an inspection chief has told a public inquiry over the crimes of Lucy Letby.

An inspection team from the Care Quality Commission (CQC) was not told of a spike in neonatal mortality or that a number of the deaths were unexpected and unexplained when they visited the hospital in mid-February 2016.

The killer nurse had already murdered five infants by then and during the inspection period she attempted to murder a baby girl, Child K, as she dislodged her breathing tube in the early hours of February 17.

A week before the inspection an external “thematic” review into 10 deaths on the unit in 2015 and January 2016 noted “some of the babies suddenly and unexpectedly deteriorated and there was no clear cause for the deterioration/death identified”.

It also found six babies had arrests between midnight and 4am but it concluded no common theme had been found in all the cases examined.

Medical director Ian Harvey and director of nursing Alison Kelly received copies of the review the day before the inspection after Mr Harvey requested it with reference to the CQC visit, the Thirlwall Inquiry has heard.

But inspectors from the healthcare regulator have told the inquiry that neither mentioned the review when they were interviewed on site.

Giving evidence on Friday, the then CQC regional head of hospital inspections Ann Ford said: “This was different.

“This wasn’t just information.

“This was about an emerging serious concern.

“It was a really, really significant issue and I think they should have made us aware of it immediately.

“Any documentation, any audits, any reviews, any work they had undertaken, should have been shared transparently and openly.

“I really do think the trust had a professional obligation and an obligation to patients to be open and transparent with us and I would have liked to have known about those concerns earlier.”

She said she first learned of an increase in neonatal mortality on June 29 2016 in a phone call from Ms Kelly after the inspection report had been published earlier that day and had rated services for children and young people as “good”.

Ms Kelly said a number of measures had been taken including downgrading the neonatal unit so intensive care babies were taken to other centres but Letby was not mentioned, said Ms Ford.

Ms Ford told the hearing: “I think we should have been alerted about the concerns of a practitioner on the unit and how they were managing that.”

The inspection chief also said that concerns had been raised by consultants during the inspection that they were being “oppressed” and “bullied” by senior management.

She said the comments were made during a focus group meeting and also included concerns about staffing levels and the trust not listening to them.

Ms Ford said she thought the feedback was later brought up by inspectors with Mr Harvey.

She said: “I understand his reaction was that they were working on culture in the trust and that he would speak to the consultant body and he would begin to address those concerns.”

Letby, 34, from Hereford, is serving 15 whole-life orders after she was convicted at Manchester Crown Court of murdering seven infants and attempting to murder seven others, with two attempts on one of her victims, between June 2015 and June 2016.

The inquiry, sitting at Liverpool Town Hall, is expected to sit until early 2025, with findings published by late autumn of that year.