Sri Lanka's police arrested 12 commandos in connection with the execution-style killing of five students during the island's Tamil separatist war, an official said Friday.

An inspector and 11 constables from the elite Police Special Task Force (STF) were taken before a magistrate in the port town of Trincomalee on Thursday, a court official told AFP.

"They were produced before the magistrate at his bungalow last night. Police had recorded their statements after arresting them yesterday," an official said, asking not to be named.

He said the 12 STF troopers were remanded in custody till July 18 pending a further hearing.

The men had been arrested in connection with the January 2006 killing of five Tamil students in the heart of Trincomalee, 260 kilometres (160 miles) northeast of the capital Columbo.

Police did not give details of the arrests which come as Sri Lanka faces international censure over its failure to prosecute those responsible for the murder of the students.

The authorities initially denied STF commandos were involved and said the students had exploded grenades and died. But a medical examination showed they had been shot execution-style.

Seven months after the murders, 17 employees of a French charity in the same district were killed by unknown gunmen in a case that is yet to be solved.

The Paris-based Action Against Hunger, or ACF, has asked the French government and the European Union, among others, to set up an international panel to probe the August 2006 massacre of its local staff.

Sri Lanka faces international questioning over its failure to probe charges that troops killed up to 40,000 civilians in the final months of fighting with Tamil rebels in 2009.

Sri Lanka has denied its forces killed civilians.