An investigation into the medical treatment of a Whanganui toddler who died in Palmerston North at the weekend is now under way.

The Palmerston North coroner's office has launched an inquiry into the death of 2-year-old Sophie-Maree Hunter, after she and her parents were twice turned away when presenting at a clinic with viral symptoms.

The reasons behind the toddler's rapid health decline were unable to be confirmed at this stage of the investigation, but it is understood Sophie-Maree's condition deteriorated within a week after her parents were told by medical staff at a clinic to go home on two occasions.

She was then seen by a Feilding GP while visiting family there and was taken to Palmerston North Hospital last Saturday.

A St John Ambulance spokesperson said paramedics picked Sophie-Maree up to take her to the airport so a Starship flying ambulance could transport her to Auckland for urgent treatment.

St John was unable to confirm when or how exactly the young girl died, or whether it was related to a particularly virulent strain of influenza that has been concerning medical professionals this winter. However, it is understood complications including septic shock arising from a pneumonia virus claimed her life as the sick little girl was en route to Auckland's Starship children's hospital.

Whanganui Regional Primary Health Organisation chief executive Judith MacDonald said that because the death had now been referred to the coroner, what was expected to be a prolonged investigation prevented her from commenting further.

A funeral service for Sophie-Maree, the daughter of Sarah and Scott Hunter, will be held in Whanganui today.

- © Fairfax NZ News