Authorities seized 18 tons of chemical precursors from India in Lazaro Cardenas, a port city in the western Mexican state of Michoacan, that were to be used to produce synthetic drugs, officials said.

Customs agents, Attorney General's Office investigators and marines staged a joint operation to seize a container shipped from the port of Jawaharlal Nehru, near Mumbai, India, to Lazaro Cardenas, a port on Mexico's Pacific coast, the Navy Secretariat and the AG's office said in a joint statement.

The container arrived in Mexico aboard the Japan, a Hong Kong-registered ship, and held 17.9 kilos of ethyl phenylacetate, a chemical used to manufacture synthetic drugs.

The AG's office took possession of the container and its cargo, which will be held as evidence in the investigation.

Authorities seized a similar quantity of the same substance last Wednesday that had arrived in Lazaro Cardenas from India aboard a Liberian-flagged vessel and was bound for Guatemala.

Mexican security forces have made some large seizures of drug precursors recently.

Army troops found more than 839 tons of drug precursors last month at a warehouse in the central city of Queretaro, the largest such seizure in Mexico's history.

The chemicals, used to make synthetic drugs such as crystal meth, were discovered on July 18 at a warehouse in the city's industrial zone, but no arrests were made.

The previous record was 200 tons of precursors seized 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 synthetic drugs.

Demand for cocaine has dropped in the United States, while use of synthetic drugs has risen because of the longer effect they produce and the fact that such drugs are considered more socially acceptable since they are taken in tablet form and not snorted, Mexican analysts and officials say.