Based on an assessment of cocaine seizures in Europe, the UN Office of Drugs and Crime (UNODC) said the flow of the drug through the region has declined from an estimated peak of 47 tonnes in 2007 to an estimated 18 tonnes in 2010.
"While this is good news, it does not take a lot of cocaine to cause trouble in a region with poverty and governance problems," the report said.
"The entire military budget of many West African countries is less than the wholesale price of a tonne of cocaine in Europe."
UNODC said in the last decade the world cocaine market has undergone a dramatic shift with demand in the US decreasing but demand in Europe doubling which has led to an upsurge in trafficking from South America through West Africa.
In 2011, the report said 30 per cent of foreigners arrested for cocaine trafficking in four European countries - Germany, Italy, Switzerland and Portugal - were from West Africa, a poverty-stricken region comprising 16 countries and some 325 million people.
UNODC expressed concern that trafficking could fund rebel forces in the Sahel and the terrorist group al-Qaeda in the Islamic Maghreb.
"Much of the cocaine headed to West Africa today comes from Brazil, where Nigerian crime groups are exporting the drug," it said.
