At least 11 people have died in clashes between inmates and guards at Sri Lanka’s Welikada prison in the capital Colombo, hospital officials say.
Dozens more were injured when police commandos came under attack while conducting a search at the prison.
Up to 4,000 inmates are held in the jail, which has seen violence before.
In January 25 prisoners and four guards were wounded when clashes erupted, and in 2010 more than 50 police and prison guards were wounded during a raid to seize mobile phones.
After the latest violence the director of the national hospital, Dr Anil Jayasinghe, told the BBC: “Ten people were brought to the hospital dead. A further 37 have been admitted suffering injuries, amongst them prison and police officers.”
A prisoner who was in the jail at the time told the BBC Sinhala’s Saroj Pathirana that clashes broke out when police commandos entered the jail, taking prisoners out of their cells and handcuffing them.
Some reports say the police may have been searching for drugs and smuggled mobile phones.
The prisoner told our correspondent that inmates seized weapons from the prison’s weapon store during the confrontation.
Eyewitness reports say inmates were seen waving rifles from the roof of a prison building. But a senior advisor to the prison ministry told BBC Sinhala that the situation was under control. (BBC)