WASHINGTON (AP) — U.S. and Colombian authorities seized $41 million in suspected drug money over the past two weeks — one of the largest seizures in the history of the countries' joint efforts, law enforcement officials said today.

The first seizure came Sept. 9 at a Colombian port where inspectors found $11.2 million in two containers. The bundles of $20 bills were tightly bound in plastic wrapping and hidden in shipments of ammonium sulfate — material commonly used for fertilizer. Using that seizure as a lead, officials went on to find nearly $30 million more at Colombian and Mexican ports over a nine-day period.

These seizures are significant because they show the sophistication of international organized criminals, which is "a warning sign for all of us," said John Morton, the head of U.S. Immigration and Customs Enforcement. The way these criminals exploited lawful trade between Colombia and Mexico is no easy task, Morton said. ICE headed the investigation that led to the initial seizure.