Mexico's government on Friday announced the seizure of more than 23 tons of drug precursor chemicals at the Pacific port of Manzanillo.

The shipment, destined for Puerto Quetzal, Guatemala, contained 136 metal barrels of methylamine, a precursor to the psychoactive drug crystal meth, and was seized on Monday, the Navy Secretariat, federal Attorney General's Office and SAT internal-revenue service said in a joint statement.

"The product is originally from Turkey. According to the entry manifest, it was loaded at the port of Cagliari, Italy, before arriving ... in Manzanillo," the statement read, adding that authorities have opened an investigation for drug trafficking.

On Thursday, Mexican authorities announced they had confiscated 205 tons of methylamine that had been shipped from China and also was destined for Puerto Quetzal.

That earlier seizure, one of the largest ever registered in Mexico, occurred at the Pacific port of Lazaro Cardenas in the first few days of December, they said.

Mexico's biggest-ever seizure of drug precursor chemicals was the confiscation of 839 tons in July at a warehouse in the central city of Queretaro, which topped the previous record of 200 tons of precursors discovered last year at Manzanillo port.

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."