Court of Appeal staff said on Friday they had received an application for permission to appeal.

No date has yet been set to hear the appeal.

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Lucy Letby: Modern Britain's most prolific child killer

She was handed 14 whole-life orders after being convicted last month, meaning she will never be allowed out of prison.

Letby, who was in her mid-20s and working at the Countess of Chester Hospital at the time of the murders, is now the UK's most prolific child killer of modern times.

The 33-year-old killed her victims by injecting the infants with insulin or air or force-feeding them with milk.

Her victims included both boys and girls, many of whom were born prematurely.

After she had killed the infants, Letby searched for 11 of the victims' families on social media and even sent one set of parents a sympathy card on the day of their baby's funeral. She took a photo of the sympathy card before she posted it.

Letby was said to be relaxed and collected despite the rising number of deaths.

At no point has she offered any motive for her crimes, leaving her victims' families still searching for answers.

Throughout her killing spree, she stuffed reams of confidential medical paperwork in reusable shopping bags, with some of these notes concerning the babies who had been killed or injured.

Letby scribbled all kinds of messages but on some of them she had written "I am evil", "I did this" and "I don't deserve to be here because I'm evil".

Prosecutors said the notes illustrated a woman in turmoil, grappling with the guilt of her actions.

Her conviction came following a harrowing 10-month trial, after which Letby refused to attend her sentencing, which the mother of one of her victims described as a "final act of wickedness".

Shortly afterwards, the government announced new plans to give judges the power to force criminals to attend their sentencing.

Read more:
PM calls Letby cowardly for not appearing in court
The psychology behind healthcare murders
How the police caught her

The Department of Health has previously said an independent inquiry will be held into Letby's case, and will examine "the circumstances surrounding the deaths and incidents - including how concerns raised by clinicians were dealt with".

Typically, applications for permission to appeal against a crown court decision are considered by a judge without a hearing.

If this is refused, people have the right to renew their bid for permission at a full court hearing before two or three judges.