A total of 136 tons of drug precursors were seized in Lazaro Cardenas, a port on Mexico's Pacific coast, where the substance arrived from China, the Navy Secretariat said.

The chemicals, which are used in manufacturing synthetic drugs, were bound for Honduras.

The substances were in 1,748 barrels packed in two containers in Lazaro Cardenas, which is in the western state of Michoacan.

The seizure was made during a joint operation staged by the Attorney General's Office, the navy and the SAT tax agency, the secretariat said.

The barrels contained "the chemical substances monomethylamine and phenyl ethyl acetate, both chemical precursors utilized to make synthetic drugs," the secretariat said.

The chemicals were turned over to the AG's office, which will conduct the drug trafficking investigation.

Mexico's biggest-ever seizure of drug precursor chemicals was the confiscation of 839 tons in July 2011 at a warehouse in the central city of Queretaro, a bust that topped the previous record of 200 tons of precursors discovered in 2010 at the 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.

Due to pressure from the security forces, some Mexican drug cartels have increased the production of synthetic drugs in Guatemala, analysts say.

Mexico's drug cartels are the main suppliers of illegal stimulants to the U.S. market.

The U.S. drug market has seen declining demand for cocaine and a simultaneous rise in demand for synthetic drugs, officials and analysts say.

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