They say the trafficking group commonly called the Medellin cartel is not an organization at all, but a loose coalition of criminals who cooperate only some of the time.

It is an established pattern of Mexican corruption that successful police commanders sell protection to one trafficking group while attacking others.

State Department and law enforcement officials said that Mexican trafficking groups and smaller Colombian cartels operating on Colombia's northern coast are now jockeying for new markets.

The amount of bulk cash shipped, as well as the vehicles, techniques, and routes used, varies, depending on the level of experience and organization of the trafficking groups involved.

The heads of the trafficking groups are known by such names as Fat Cat and Mustafa and Prince.

In some cases the trafficking groups were loose confederations of businessmen and smugglers who associated for a single deal.

The agency described the trafficking groups as ranging from loose confederations of businessmen and smugglers who associate for a single deal, to more complex organizations of up to 100 people.

The Medellin group is competing for the New York market with another Colombian trafficking group based in the city of Cali.

But things have changed in three years : the market has grown, and new trafficking groups want to have a place in the market.

Increasingly, Chinese trafficking groups based in Bangkok, Hong Kong and New York have taken over the New York heroin market.