By Stephen Gibbs
BBC News, Mexico City
**Mexican authorities say they have made their largest-ever seizure of chemicals used in the manufacturer of the synthetic drug methamphetamine.**A total of 37 tonnes were confiscated in two separate raids in different parts of the country.
Mexico, one of the world’s leading producers of the drug, says the seizure represents a blow to organised crime.
Some 20 tonnes of the psycho-stimulant drug were found on a boat entering the Pacific Coast port of Manzanillo.
A further 17 tonnes were uncovered in the city of Nuevo Laredo, close to the border with Texas.
Several arrests are understood to have been made.
Both the Mexican and US authorities have recently pointed to the fact that drug cartels in Mexico are increasingly diversifying their business into the manufacture and trafficking of methamphetamine.
It has the advantage over cocaine that it can be domestically produced in large quantities.
The precursor chemicals required to make the drug are, however, usually imported.
It is that part of the business which the Mexican authorities are currently targeting.