The UN office on drugs and crime said 437,000 people were murdered in 2012, compared to 468,000 in 2010, the first year its global study on homicide was conducted.
Central America and southern Africa had rates of 26 and 30 people killed for every 100,000, more than four times the world average.
Half of all victims were under 30, 80 per cent were men as were 95 per cent of perpetrators, UNODC said.
While men tended to be killed by an unknown assailant, women were most often murdered by somebody close to them, the report noted.
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In North and Latin America, gang-related homicides made up 30 per cent of the total, compared to less than one percent in Asia, Europe and Oceania, where the share of murders from domestic violence was higher.
UNODC also found that only 43 per cent of murders resulted in a conviction.