One of the prisoners at the centre of accusations of violence at Serco-run Mt Eden Prison says he was beaten by four prisoners and dropped off a balcony.

Photo: RNZ

Alex Littleton, who broke both his legs in February, is now at Kaitoke Prison near Whanganui.

In a recording obtained by Radio New Zealand, Littleton said he crawled to a guard window for help during the incident but received no immediate response.

The 29-year-old said it was not until his attackers were stomping on his head that a guard finally intervened.

"I was thrown off the balcony and I was attacked in the room by four prisoners. There's no way that one person can get - can do anything like that to me," he said.

"There's not anyone then in that whole entire prison that could do that... It's a token that people are getting beaten up in there all the time."

Littleton said Serco discharged him from hospital four weeks early, saying they could care for him in prison.

He said he was not given night medication and, on the first night, soiled the bed because he could not walk.

Littleton's mother, Lorraine Pehi-Littleton, said that was "very distressing" for her to hear.

"I was in the hospital with Alex the day that Serco took him out and I was fuming, because I knew he wasn't ready. He couldn't even walk or anything."

Ms Pehi-Littleton said the doctors assured her that her son would get the same treatment back in the prison.

Serco has said there is no evidence to support allegations of prisoners being dropped.

It is yet to respond to Radio New Zealand's questions about Alex Littleton's claims.

Corrections has formally taken over the management of the privately-run prison while a string of allegations, including a fight club, contraband, prisoner injuries and the death of an inmate, is investigated.

It has also fined Serco $500,000 for failing to meet performance targets.

The department has said it hopes the report by the Chief Inspector of Prisons will be completed by the end of August.