Police say they have arrested a 28-year-old Nigerian carrying a half million dollars' worth of cocaine stashed in speakers that he carried from Sao Paolo, in Brazil, to the northern Nigerian city of Kano.

Commandant Ambrose Umoru said Maduagwu Nnaemeka was arrested at Kano International Airport on Wednesday with 3 kilograms (6.6 pounds) of pure cocaine with a street value of 81 million naira.

Nnaemeka told reporters at a news conference Wednesday that he was given the speakers at Sao Paolo airport by a Nigerian stranger who begged him to carry them to Kano. He said he knew nothing about the cocaine they carried.

The U.N. Office on Drugs and Crimes estimates between 25 and 66 percent of cocaine bound for Europe from South America passes through West Africa.