According to a report by the World Bank and UNODC , around 20 to 30 drug traffickers , the majority operating in southern Afghanistan , control most of the trade and they could not operate without a close association with the main Taliban commanders in the region , 20 of whom are also regarded by security authorities in Afghanistan as serious traffickers .
The above sentence is very complicated. Please provide me a simplified synonymous version consisting of multiple sentences:
According to a report issued by the World Bank and the United Nations Office on Drugs and Crime , about 20 to 30 drug traffickers , most of whom work in southern Afghanistan , control the bulk of the trade ( ) , and cannot operate without close association with the main Taliban leaders in the region . The Afghan security authorities also consider 20 of them to be major drug traffickers ( ) .