Almost 70 prisoners and staff have been assaulted at Christchurch Men's Prison just this year.

The most recent occurred just two days ago, when the man accused of of assaulting and murdering Christchurch toddler Ihaka Stokes was set on by inmates.

As of last month, 67 assaults were recorded by corrections.

Two of them were classified as serious, 40 of them resulted in minor injuries, and 25 were at the lower end of the scale.

Acting Southern Regional Commissioner Natasha Possenniskie said the department has a zero tolerance policy toward prisoner assaults.

However, she adds it's an unfortunate reality that they'll occur from time to time.