A Corrections Department officer attacked at Rimutaka Prison near Wellington remains in an induced coma.

The officer was taken to hospital after he was attacked when he went to the aid of a low-security prisoner who was being attacked by a group of inmates on Friday.

A Department of Corrections spokeswoman said the officer was in an induced coma at a hospital which she would not name.

She said he was in a serious but stable condition. His injuries were not considered to be life threatening.

"I think he's got a long recovery road to go but everyone sounds positive," she said.

An inmate who was injured in the scuffle has been returned to prison.

Corrections chief executive Ray Smith says an investigation has been launched into the incident, and police have been informed.