An investigation is underway after a woman who called 111 died before receiving a call back from a doctor.

The patient’s condition deteriorated rapidly from the time she called the non-emergency medical number with a health issue.

And when an ambulance arrived at her address on December 22 they attempted CPR but they could revive the 33-year-old.

Harmoni, which runs the NHS 111 service in south west London, is leading the investigation into her death.

The company’s national medical director of urgent care, Dr David Lee, said: “We would like to offer our sincerest condolences to the family for their tragic loss.

“We notified Croydon Clinical Commissioning Group of the incident and, as is the case with any unexpected death, a multi-agency investigation was immediately launched.

“Early findings suggest that this was a complex case assessed through NHS 111 including input from a clinician and that there was an unexpected and rapid deterioration in the patient.

“However, while the investigation remains ongoing and until all the facts are known, we cannot comment any further.”

Dr Agnelo Fernandes, assistant clinical chairman at Croydon CCG, said: “We are taking this matter seriously, and our sympathies are with the friends and family of the individual involved at what must be a very difficult time.

"As the commissioner of this service we have ordered a detailed investigation which is now under way, and we will be able to say more once that investigation has been completed.”

Harmoni is expected to give the results of the investigation to the clinical commissioning group by March 7.