A rights group report on Tuesday blamed local security forces for the massacre of 17 Sri Lankan tsunami aid workers in 2006 and accused the government of an outright coverup. At the time, the killing of the local workers from aid group Action Contre La Faim (ACF) in the island's northeast was the worst attack on humanitarian workers since the 2003 bombing of the United Nations compound in Baghdad. The mainly ethnic Tamil workers, who had been involved in rebuilding after the 2004 tsunami, were found shot in the head and lying face down in the ACF compound in the predominantly Muslim town of Mutur in August 2006. The military said they were trapped in fighting between troops and rebels. The University Teachers for Human Rights (UTHR), a Sri Lankan group that has been criticized by both sides throughout the two decade civil war, named a local Muslim home guard - a police auxiliary - and two constables as the killers of most of the group. “The evidence shows state security forces, including police, killed the 17 aid workers and that senior police officers covered it up,” said Rajan Hoole of UTHR. “The killing of civilians during time of conflict is a war crime. The perpetrators and their superiors should be brought to justice.” Most Mutur residents had fled the town by the time of the massacre. The first aid team into the town days later found the bloated bodies in the ACF compound, most shot at close range. The Sri Lankan government has denied responsibility and blamed the Liberation Tigers of Tamil Eelam (LTTE). International monitors recently told the government they were withdrawing from the inquiry because of official interference and lack of internationally acceptable standards. The report said the brother of a Muslim home guard had been killed by a Tiger gunman the previous day and he had vowed revenge. It also said a special forces commander in the town ordered security forces to “finish off” any Tamil speakers in plain clothes if they had any suspicions after another rebel disguised as a civilian killed troops. It said witnesses described an “air of celebration” at Mutur police station after the massacre, adding that the anger of the Muslim home guard appeared to have simply been “a pretext” and senior figures in the nearby northeastern town of Trincomalee apparently also backed the unwanted killings. The report said the execution-style murder of five Tamil students in Trincomalee earlier in 2006 had also been covered up and one of the responsible officers promoted, fostering a culture of impunity as a 2002 ceasefire collapsed into open war. International group Human Rights Watch described the report as a “brilliant piece of investigative work”. “It does more than name the names of those responsible for the brutal ACF killings,” said Human Rights Watch senior legal adviser James Ross. “It shows the government investigations into the massacre were little more than a bad joke played out on the victims' families and the international community.” UTHR said publishing the report was not without risk, particularly as three witnesses had already been killed, a fourth had gone missing and others fled the country - part of a wider pattern of disappearances and killings. __