Regime forces have encircled a prison in the central Syrian city of Hama as prisoners reportedly took captive the warden and several guards during heavy clashes.
The prison uprising broke out in response to the regime's plans to forcibly transfer several detainees to Sednaya, an infamous prison near Damascus, sources inside the jail told Al Jazeera.
Regime forces have surrounded the prison and fired tear gas in an effort to quell the unrest, according to sources in the jail and the UK-based Syrian Observatory for Human Rights.
The Observatory said the prisoners, many of whom are detained without charge, demanded "basic rights", including a fair trial or release.
In response, the Ajnad al-Sham opposition group vowed to attack regime forces and armed groups loyal to Bashar al-Assad if the prisoners' demands were not met.
In a statement released on Monday night, Ajnad al-Sham claimed the regime had threatened to "storm the prison and execute all the prisoners without a trial".
The group added: "Our brothers inside the prison are still carrying out the uprising and have taken complete control of the building. We in Ajnad al-Sham declare... our full readiness to strike [regime-allied] militias in Maharda and al-Suqaylabiyah."
The state news agency SANA said an official in the interior ministry had dismissed claims "in some media" about an uprising in the prison.
The Syrian conflict started as a largely unarmed uprising in March 2011, but it quickly morphed into a full-on war against the Syrian people.
United Nations special envoy to Syria Steffan de Mistura recently estimated that more than 400,000 people had been killed throughout the fighting.
International and Syrian human rights organizations have decried conditions inside Syrian prisons before and during the war.
Between March 2011 and the end of 2015, the Syrian Network for Human Rights documented the arrest and detention of more than 117,000 people.
In a December 2015 report, Human Rights Watch (HRW) said its researchers had found "evidence of widespread torture, starvation, beatings, and disease" in government jails and detention centers.
"Many of the former detainees who were held in these nightmarish conditions told us they often wished they would die, rather than continue suffering," said Nadim Houry, deputy Middle East director at HRW.
"They begged countries involved in seeking a peace process to do everything they can to help the people still being held in Syria."
PHOTO CAPTION
A rebel fighter fires a weapon towards forces loyal to Bashar al-Assad in the town of Morek, Hama province. [Reuters, May 13, 2015]
Source: Al Jazeera