A second riot broke out the El Abra prison in Cochabamba, Bolivia on Wednesday, following a riot on Sunday night when four inmates were killed and eleven injured.

The unrest was staged in an effort to prevent policemen from entering, inspecting and seizing banned items from prison quarters following Sunday's shootout.

Inmates say the prison was rife with abuse by other prisoners involved in gangs.

"A lot of abuse was taking place before this. That is why we are upset. When a new inmate enters the prison they (prison leaders) ask for extortion money as a life insurance. They treat us as though we are objects having to pay when we are inside. We pay from $2,000 to $3,000," she said.

Some sharp objects such as firearms, knives, steel rods, as well as cocaine and marijuana have already been seized by the police from the inmates.

Al Jazeera's Adam Raney reports.