Sri Lankan authorities are investigating unrest and violence at five prisons after at least three inmates were killed. Public Security Minister Ananda Wijepala told parliament on Friday that incidents had recently occurred at Negombo, Mahara, Magazine, Kuruwita and Pallansena prisons, raising suspicions of coordinated action, possible sabotage and a broader conspiracy.

Wijepala said the incidents, considered together, appeared to be planned sabotage and part of a conspiracy. Preliminary investigations indicated that activities by drug and criminal networks could be the immediate cause of the unrest. Authorities said they were examining whether the incidents shared the same planning or coordinated operation.

At Pallansena prison on Friday, inmates climbed onto a roof and began protesting before police used tear gas to restore control; the reason for the protest was not immediately known. Tensions also spread at Kuruwita, where at least two people were killed and more than a dozen injured. On Thursday night, about 40 inmates left a ward at Magazine prison, where one inmate was killed and 10 others were hospitalized.