The zoo said the woman's arm was injured about 12.50pm during a routine daily procedure with southern white rhino Kai.

The zoo keeper received first aid at the scene and the paramedics were called.

Kai was uninjured in the incident, which happened in a part of the zoo that is not open to the public.

A NSW Ambulance spokesman said the woman was being flown to Canberra Hospital.

He said paramedics were called about 1pm after reports a 47-year-old woman had been gored by a rhino in the arm.

She was treated for a penetrated wound in her left arm, which was also thought to be fractured.

She was understood to be in a stable condition, and was conscious and alert.

Zoo owner Sally Padey said: "Whilst all safety measures are taken to minimise risk for both animals and keepers occasionally accidents can occur when dealing with large mega fauna".

The zoo said it would review its standard operating procedures and had launched an internal investigation into the incident.

The zoo remains open to the public.

Mogo Zoo has two southern white rhinos, which arrived there in early 2015.

Half-brothers Kai and Jabari, both aged 11, weighed about four tonnes each at that point, and were about 1.8 metres tall.

According to the zoo's website, white rhinos are among the heaviest land animals in the world.

The private zoo made headlines in 2009 when staff shot dead an escaped lioness.

About 35 visitors had been exploring nearby exhibits when Jameila, a nine-year-old 190-kilogram female tawny lion, escaped her enclosure in March 2009.

Ms Padey made the heartbreaking decision to have the animal she had helped rear shot dead.