The United States on Friday urged Sri Lanka to investigate a deadly army crackdown on a village environmental protest and to prosecute those responsible.
The military on August 1 opened fire on thousands of unarmed villagers at Weliweriya near Colombo as they protested contamination of their ground water, allegedly due to chemical waste from a rubber glove factory.
US officials "urge all sides to exercise restraint and urge the authorities to respect the right of peaceful protest," State Department spokeswoman Jen Psaki said in a statement.
"We call for a thorough and transparent inquiry into all aspects of the Weliweriya violence, for those conclusions to be made public, and for there to be a credible mechanism to prosecute any wrongdoing," she said.
Psaki voiced particular concern at accounts that protesters were attacked after seeking refuge inside a Roman Catholic church.
At least three civilians died and another 50 were injured. Sri Lanka's opposition has urged an international investigation after the army promised an internal probe.
US relations with Sri Lanka have deteriorated since 2009, when the military was accused of human rights abuses as it defeated the Tamil Tigers, a separatist group itself known for bloody assaults.
The United States has repeatedly accused Sri Lanka of doing too little to ensure accountability.
New York-based advocacy group Human Rights Watch also called for an independent investigation into the village crackdown and questioned why armed soldiers would be sent to a demonstration.
"The government needs to rethink its whole approach to ensure that people can peacefully and safely protest, the group's South Asia director, Meenakshi Ganguly, said in a statement.