Mexican authorities seized a total of 205 tons of drug precursor chemicals at the Pacific port of Lazaro Cardenas, officials said Thursday.

The chemicals, shipped from China and destined for Puerto Quetzal, Guatemala, were confiscated in early December, the Navy Secretariat, federal Attorney General's Office and SAT internal-revenue service said in a joint statement.

The drug precursor chemicals were found in 3,152 plastic barrels that had been distributed among 11 cargo containers and were discovered during the transshipment process.

After a series of tests, the authorities discovered that the substance being shipped was methylamine, which the U.S. Drug Enforcement Administration lists as a precursor to methamphetamine.

The seizure of the chemicals, which were subsequently turned over to the federal AG's Office, was one of the largest confiscations of its kind in Mexico.

By far the biggest was the seizure in July of 839 tons of drug precursors at a warehouse in the central city of Queretaro, which topped the previous record of 200 tons of precursors discovered last year in the Pacific port of Manzanillo.

Mexico, which produces most of the crystal meth consumed in the United States, has imposed tight restrictions on the import of chemicals used to make illegal synthetic drugs.

Thus far this year, the administration of President Felipe Calderon, who militarized the struggle against violent drug cartels after taking office in late 2006, has seized some 2,000 tons of drug precursor chemicals.

According to authorities and analysts, the U.S. drug market has seen declining demand for cocaine and a simultaneous rise in demand for synthetic drugs.

Those narcotics are favored by users for their more prolonged effect and because they come in tablet form and are therefore considered "socially cleaner."

Separately, the Mexican army on Wednesday discovered a shipment of 3.75 tons of marijuana abandoned on a beach in the northwestern state of Baja California, a top military officer said.

Gen. Gilberto Briseño Landeros, commander of the 2nd Military Zone, told reporters the shipment was found on La Burrita beach in the town of Playas de Rosarito, 35 kilometers (21 miles) south of the U.S.-Mexico border.

The marijuana had been distributed among 222 cylindrical packets, he said, adding that no arrests were made in the operation.

The general did not indicate which drug cartel may have been behind the shipment and said he did not know why it had been left on the beach. EFE