Corrections is carrying out a review after eleven inmates at Spring Hill Prison rioted and started fires in the exercise yard - prompting a lockdown

Emergency services arrived at the Waikato Corrections facility at about 3.30 yesterday afternoon when a group of prisoners refused to leave the exercise area and lit small fires.

Corrections says two hours later at about 5.30pm all the inmates had left the yard and the fires were put out.

It says the behaviour will not be tolerated and and those involved will be held to account.