Mexican authorities said they have seized nearly 3 tons of pseudoephedrine from a ship that arrived from South Korea.
Soldiers and federal agents have found 8 million pseudoephedrine tablets weighing 2.8 tons in 60 boxes aboard a ship in the Pacific port of Manzanillo.
Pseudoephedrine is the main ingredient used to make methamphetamine.
The bust occurred Monday and was announced Thursday in a joint statement from the Attorney General's Office, the navy and departments of defense and public safety.
Mexico has banned all imports of pseudoephedrine to try to thwart methamphetamine production. The U.S. Justice Department says Mexican traffickers are the main methamphetamine suppliers to the United States.