Several people were injured when a clash erupted between prison guards and inmates of the main prison near the capital Colombo on Tuesday, a prisons official said.
Prisons Commissioner P.W Kodippili said that the clash erupted following a protest by a group of prisoners.
Initial reports indicated the prisoners were angry over the poor condition of the food served to the prisoners.
The protest went out of control and 31 people were injured in the ensuing clash and were rushed to hospital.
Doctors at the Colombo national hospital said that a majority of the prisoners who were injured had sustained gun-shot injuries to the leg.
However Kodippili insisted that the prison guards fired in the air in order to control the violence which had erupted.
Following the clash some prisoners got on top of the prison roof and began pelting stones towards the main road opposite the prison disrupting traffic.
The police closed the road and the military was called in to bring the situation under control, a military spokesman said.
The police later fire tear gas at the prisoners.