Crime gangs have stolen dozens of truckloads of copper owned by miners and traders including Glencore, Trafigura and Traxys this year as they were heading to ports in southern Africa, three sources with direct knowledge of the matter said. Record high copper prices have triggered an increase in hijackings in recent months in Botswana, the Democratic Republic of Congo, South Africa, Tanzania and Zambia, said the sources who declined to be named due to the sensitivity of the matter.