The UN drugs watchdog has warned that food shortages in Africa are becoming more serious because of a shift from growing crops to cultivating cannabis.
Cannabis remains the most widely grown drug on the continent
In its annual report, the International Narcotics Control Board says the main producers of the drug are southern countries like South Africa and Malawi.
But, it says, farmers in east Africa and Sudan have also switched.
The report says profits from cannabis and other illegal drugs have been used to finance some of Africa's conflicts.
The UN says drug money was used to buy weapons for wars in Ivory Coast, Liberia and the Central African Republic.
Hard drug use was also increasing, but cannabis remained the most widely grown, traded and consumed drug on the continent, the report said.
Although farmers earn more money from growing cannabis than traditional food crops, the switch means there is less food available in local markets, the INCB's Beate Hammond told BBC News Online.
"Imported food is more expensive," she said.
The food shortages resulting from the switch were most serious in Sudan, she said.
A quarter of all cannabis confiscated by the authorities was found in Africa, and the bulk of this was seized by South Africa.
"The economic and environmental impact of cannabis cultivation, particularly the abandonment of traditional crops, as well as deforestation, are of great concern," it said.
The report also cites Morocco as one of the world's leading producers, with most smugglers taking the drug to Europe via Spain.
But anti-drugs measures by Spanish and Portuguese police meant traffickers were looking to routes through other North and sub-Saharan African countries.
Cannabis is also being smuggled across the Red Sea to Saudi Arabia and other Arab countries, the report said.