LONDON — Global murder rates have declined slightly but remain very high in the Americas and parts of Africa, according to a UN study released Thursday.
Homicide rates in southern Africa and Central America are more than four times higher than the global average of 6.2 victims per 100,000 people, the UN Office on Drugs and Crime report said. The figures chronicle murder rates in 2012. It found more than half of all victims were younger than 30.
UN policy analyst Jean-Luc Lemahieu said the figures show that Canada and the United States remain below the global average but some countries in Central and South America are far higher.
‘‘The Americas remain a very violent part of the world,’’ Lemahieu said, citing high murder rates in Honduras, Belize, El Salvador, Colombia, Venezuela, and Mexico.
He said violence between drug cartels has contributed to the troubles in Mexico, where the homicide rate has roughly doubled since 2007.
Lemahieu said South Africa still has a murder rate of about 31 per 100,000 people — far higher than the norm — but has seen a steady reduction in the last five years.
Rates are lowest in Europe, Asia, and Oceania, according to the report. It estimates that only about 43 percent of murders end with a conviction of the person responsible.