After more than 40 years, the former US army officer found guilty of organizing mass killings in the Vietnamese community of My Lai during the war has made a public apology. 'There is not a day that goes by that I do not feel remorse for what happened that day in My Lai,' former lieutenant William Calley told members of the Kiwanis Club of Greater Columbus, Georgia. 'I feel remorse for the Vietnamese who were killed, for their families, for the American soldiers involved and their families. I am very sorry.' Calley spoke on Wednesday, but due to a restricted audience his remarks did not become known until now. The killings that occurred on March 16, 1968 in the South Vietnamese hamlet of My Lai prompted widespread outrage around the world. They are also credited with advancing the end of the Vietnam War because they significantly undercut US public support for the war effort. The massacre began when men of Charlie Company under the command of Lieutenant Calley opened fire on civilians during a 'search and destroy' mission in My Lai and neighboring villages. The targets of the killings were mainly old men, women and children -- all unarmed -- as most younger members of the community were working in the fields. The exact toll of the massacre still remain in dispute. But US estimates suggest that between 347 and 504 unarmed citizens were massacred that day. 