A prison in Siberia reported disturbances at a high-security penal colony Friday, while local campaigners called the incident a full-blown riot and posted images of fire on the premises.

Russia’s penal service said inmates at the No 15 penal colony in Angarsk “attacked a guard” while others cut themselves with glass from broken surveillance cameras.

The service said the guard was hospitalised and the mutiny, which broke out on Thursday, was under control, while investigators opened a probe on charges of disrupting prison work.

Human rights activists however called the incident a “riot” sparked by a beating of an inmate by guards, and said the incident was far from over.

Rights group For Human Rights on Thursday published a video link on its website of the inmate with bloody gauze around his arm, who says he was choked and beaten, and cut his veins in protest.

An activist with anti-torture group Siberia Without Torture Svyatoslav Khromenkov told AFP that riot police encircled the colony and was turning passing cars around, while a fire was raging on colony grounds.

In videos seen by AFP that Khromenkov said were sent by prisoners to his organisation, inmates are seen standing in the work yard of the prison, part of which is on fire. 

“They are killing us,” the man filming says of the guards, as other men shout “Help us!”, show their arms with knife marks, and claim that two inmates were killed.

Khromenkov said it wasn’t clear whether the riot was related to stricter quarantine measures prison authorities have enforced in Russia.