"This was a clash between LTTE suspects triggered by an argument due to personal reasons", PW Kodippily, the superintendent of prisons told reporters.
"Two of them have already been discharged from hospital. We have sent a senior prison official from Anuradhapura to investigate and report", Kodippily added.
The LTTE suspects often cause unrest in jails across the island. They demand their cases be expedited.
The government pledged last month to set up two special courts to deal with the backlog of cases against the LTTE suspects.