A top United Nations official says drug traffickers are using a more sophisticated system to smuggle drugs from West Africa to Europe.

Alexander Schmidt, the West African head of the U.N. Office on Drug Crime, says the amount of cocaine seized in western Africa has gone down, suggesting that smugglers are repositioning drug routes and becoming increasingly sophisticated at hiding their operations.

Schmidt says officials also believe cartels are using lightweight submarines similar to ones seen off the South American and the Caribbean coasts.

Schmidt says although a few Latin Americans still dominate the trade, West Africans are starting to have increasingly influential roles.

He places the value of the drugs passing through West Africa at $800 million.

Schmidt spoke Monday at a meeting of the policy committee of the West Africa Coast Initiative. The group, made up of UN officials, government ministers and Interpol representatives, aims to tackle drug trafficking and organized crime in West Africa.