In a massacre that shocked the world's humanitarian community, 17 aid workers were killed a decade ago outside their office in northeast Sri Lanka — executed at point-blank range with automatic weapons in one of the worst attacks on humanitarians.

Justice remains elusive for families of the victims, all Sri Lankan, says Action Contra la Faim (ACF), the charity where they worked.

"Our colleagues, four women and 13 men, were deliberately executed although they were clearly identified as humanitarian aid workers. It was an unprecedented massacre in the humanitarian sector, constitutive of a war crime," said Pauline Chetcuti, ACF's head of humanitarian advocacy and policy.