About 50 tonnes of cocaine are shipped through West Africa each year
The new head of Guinea's anti-drugs unit has told the BBC that some of his agents are corrupt.
Police Commissioner Moussa Sackho Camara said that some suspected drugs traffickers had been freed from detention without his knowledge.
He also said that when he took over in August, some junior agents had parked their limousines outside the office.
West Africa is increasingly being used by smugglers to transport cocaine from Latin America to Europe.
Last month, the governor, mayor and other top police officials were arrested in the town of Boke in northern Guinea, after an aircraft allegedly carrying a large quantity of cocaine mysteriously landed and took off.
Mr Camara said that the fight against drug trafficking was a tough one, given the highly placed people involved in the business on the one hand, and the lack of equipment on the other.
"This is a war and our enemies are well armed and well placed, coming from the air, land and sea," he told the BBC's Alhassan Sillah in Conakry.
"Some of my own agents are collaborators of the drug pushers."
Mr Camara said that when he saw the limousines in the car-park:
"I gave orders that I never again wanted to see these cars in my work place. Since then, I haven't seen these cars or some of these agents."
Large seizures of cocaine have been made recently in neighbouring countries, such as Guinea-Bissau, Senegal and Sierra Leone.
Law enforcements agents say Latin American drug traffickers have switched to using West Africa, as traditional routes such as through the Caribbean have become better policed.
They say the poverty, instability and weak institutions make some West African states vulnerable to the wealthy drugs barons.
The UN estimates that at least 50 tonnes of cocaine are shipped through the region every year.