Sri Lanka is among the most dangerous places on earth for humanitarian workers, the UN’s aid chief says, calling on the government to probe civil war abuses and consider an international rights monitoring mission. Aid agencies say 34 humanitarian staff have been killed in Sri Lanka since January 2006, including 17 local staff of Action Contre La Faim shot dead in the restive northeast a year ago in a massacre Nordic truce monitors blamed on security forces. “There is a concern ... about the safety of humanitarian workers themselves and the record here is one of the worst in the world from that point of view,” John Holmes, UN Under Secretary General for Humanitarian Affairs, told Reuters in an interview late on Wednesday during a visit to Sri Lanka.