Former British nurse Lucy Letby, who is serving a whole life sentence in prison for murdering seven babies in her care, has been questioned about the deaths of more infants, police said on Wednesday.

Letby, 34, was found guilty last year of killing the newborns and attempting to murder seven more between June 2015 and June 2016 while working in the neonatal unit of the Countess of Chester Hospital in Chester, northern England, making her Britain's worst serial child killer of modern times.

NURSE LUCY LETBY 'CAUGHT VIRTUALLY RED-HANDED' DISLODGING PREMATURE BABY'S BREATHING TUBE: PROSECUTORS

She was convicted of an eighth count of attempted murder at a retrial earlier this year.

At the time of her conviction, police said they were carrying out further investigations into the whole time Letby had worked as a nurse at the hospital and at another one in Liverpool, where she had trained, to identify if there were any more victims.

"We can confirm that, following agreement, Lucy Letby has recently been interviewed in prison under caution in relation to the ongoing investigation into baby deaths and non-fatal collapses at the Countess of Chester Hospital and the Liverpool Women’s Hospital," Cheshire Police said in a statement.

The force said further updates would follow at the appropriate time.

Currently a public inquiry is underway into how the killings went undetected, and to review the hospital's response to concerns raised by doctors about Letby before her arrest.

Since her trials, Letby's case has faced criticism by some experts of the medical and statistical evidence presented by the prosecution, with some media questioning whether she might be the victim of a miscarriage of justice.

However, London's Court of Appeal has rejected her attempts to overturn her convictions.