The terrible toll of Mexico's war

Part of the challenge for the Mexican government is that that drug syndicates are funded from the profits of a hugely lucrative market.

It is impossible to put an accurate figure on the value of the global drug trade for, self evidently, criminal networks do not report on their activities.

However, in 2005 the United Nations Office on Drugs and Crime estimated that at that time drug production was worth approximately $13 billion, increasing in value to almost $100 billion at the wholesale stage and more than $300 billion at the street level.

Ironically, the Mexican cartels are believed to have grown in strength after the successful efforts of the Colombian government and international law enforcement agencies to quell the activities of Colombian drug barons.

Mexican networks, previously sub-contracted by the Colombian drug lords to transport drugs, have moved to fill the void left after the Colombian crackdown.

The cartels are assumed to have taken control of large parts of the supply chain, with the drug wars spreading to other parts of Central America.

Mexico President Felipe Calderón describes the murderous activities of the cartels as an attempt to take over the actual running of the country.

Since coming to power in late 2006 Calderon has deployed large numbers of police and military against the cartels.

While there has been some success in capturing a number of the leading figures, others have quickly filled the roles, and the flow of blood on the streets of key Mexican cities continues unabated.

In a deeply worrying incident on 24 April this year, a car was set alight during office hours outside a building housing the State Attorney General in Nuevo Laredo.

Soldiers from the Mexico army were deployed to the area and quickly came under attack from cartel gunmen.

While no soldiers were killed, the incident attracted attention as it appeared to be a deliberate ploy by the cartels to engage directly with the Mexican military.