As government troops beef up security following a weekend jail riot, the country's main opposition has demanded an independent inquiry into the incident, which left 27 convicts dead.
The United National Party (UNP) on Sunday called for a parliamentary investigation into the riot that erupted on Friday evening and carried on into Saturday morning at the maximum-security Welikada prison in the capital Colombo.
"This is nothing but a massacre," UNP spokesman Mangala Samaraweera told the AFP news agency. "Most of the convicts appeared to have been killed in cold blood. We want a parliamentary select committee to go into this."
Meanwhile, security in the capital has been beefed up following the riot, which spilled onto the streets in fierce clashes between inmates and police.
During the riot, armed inmates climbed onto the roof and fired at troops and police. A handful escaped and hijacked a three-wheel rickshaw taxi, which was stopped by heavy gunfire from security personnel.
Prisons Minister Chandrasiri Gajadeera told parliament on Saturday that 27 inmates were killed and 43 others - including 13 police commandos, four soldiers and two civilians - were injured.
He said there would be an internal prisons department inquiry into the riot, which was sparked by a police commando raid for contraband inside the prison on Friday.
The violence continued until early on Saturday with some prisoners raiding a jail armoury and grabbing about 80 weapons, including automatic rifles.
Prisons chief P W Koddippili said guards were searching the site Sunday for a small number of guns which were still missing. Officials declined to say if any prisoners had escaped during the unrest.
Friday's violence was the worst prison riot in Sri Lanka since 1983, when more than 50 ethnic Tamil prisoners were massacred at the same jail by Sinhalese convicts during anti-Tamil riots that gripped the country.
There was similar violence at the same penitentiary in January when 25 inmates and four guards were injured.
The authorities have yet to release autopsy reports on the dead. Colombo police chief Anura Senanayake said most of those killed were hard-core criminals, some of them serving life terms.
The opposition UNP also demanded answers from the government on how the armed forces were deployed at the weekend, when emergency laws were no longer in operation after the end of the country's ethnic war in 2009.