Letby was last month found guilty of killing five baby boys and two baby girls at the neonatal unit of Countess of Chester hospital in northern England over 13 months from 2015, injecting the infants with insulin or air or force feeding them milk.

The 33-year-old was sentenced at Manchester Crown Court to a whole-life order last month, meaning she will never be released from prison.

Letby has filed an application for leave to appeal against her conviction at London's Court of Appeal, a court spokesperson said. No date for any appeal has been set, they added.

(Reporting by Sam Tobin; Editing by Alistair Smout)