At least 60,000 people have died in government prisons during Syria's five-year war from torture, starvation and other causes
Syrian prison inmates in Hama rioted on Saturday for a second time this month, holding its director and a police chief hostage and demanding to be released, a monitor said.
"A new riot started in the central Hama prison appearing to be more serious than the previous one as the prisoners were able to detain the director of the prison, the head of police in Hama city and nine policemen," the Syrian Observatory for Human Rights said.
A raid by security forces on the prison in the central city of Hama earlier this month failed to end a mutiny involving around 800 inmates who activists said were mostly political detainees.
Detainees took 10 guards hostage in that riot, which started after an attempt to transfer inmates to another prison near Damascus, where numerous executions of prisoners have been reported.
After that protest, the Damascus government agreed to release all of the prisoners, Observatory chief Rami Abdel Rahman said.
It set free more than 100 detainees, but a further 700 remain inside after the government decided not to release them immediately but to send them to trial instead, he said.
Footage circulated online on Saturday appears to show dozens of inmates in a corridor inside the prison shouting: "God is the greatest."
"The director and the police chief and some policemen were captured on May 28 at 2pm," a voice is heard saying.
Authorities have cut water and electricity in response to the riot, Abdel Rahman said.
More than 200,000 people have spent time in Syrian government prisons since 2011, according to the Britain-based Observatory, which relies on a network of sources inside Syria for its information.
At least 60,000 people have died in government prisons during Syria's five-year war from torture or because of dire humanitarian conditions, including a lack of food.