Prison system so stretched it would be unable to cope with riots or natural disasters

New Zealand's prison system is so stretched it won't be able to cope with a natural disaster or riot, documents released today have revealed.

It comes after a decision was made not to build a planned mega-prison in Waikeria, near Hamilton.

The scale of the problem is outlined in the documents, which show most of the 900 prison beds set aside for a disaster are currently full.

There are also concerns the "extreme overcrowding" could have an impact on staff safety, as well as increase the levels of violence, disorder and suicide rates behind bars.

The papers suggest more double bunking, even in smaller cells, would help ease the pressure on the prison system.

The government also has plans to reduce the prison population.