Disorder has broken out at a prison for the third time in eleven days.
Serco, which runs HMP Lowdham Grange in Nottinghamshire, said aggression by a "handful" of prisoners at Lowdham Grange on Monday afternoon was quickly brought under control.
The other recent disturbances there, on 26 and 31 July, both lasted for several hours and there were reports stun grenades were used to end the violence.
The "small disturbance" was "over in five minutes", a Serco spokesman said.
Both previous outbreaks were "peacefully resolved" and involved only a small number of prisoners, Serco said.