Pemex workers inspect an oil siphon

Hydrocarbon theft in Mexico so far this year has nearly doubled in comparison with 2012, with the worst hit zones corresponding to some of Mexico's drug war hotspots.

In the first four months of 2013, Mexican state oil company Pemex recorded 730 illegal siphons, in comparison to 377 last year, reported La Jornada. Of those siphons, 666 targeted pipelines operated by Pemex's oil refining arm, 40 its gas and petro-chemicals arm and 24 from Pemex Exploration and Production.

The worst hit states were Tamaulipas, Veracruz, Sinaloa, the state of Mexico and Jalisco. Authorities have arrested 48 people for siphoning, and 180 more for transporting illegal fuel, so far this year.

Between 2011 and 2012, the number of illegal siphons detected jumped 23.2 percent, from 1,416 to 1,744. Pemex attributed the rise predominantly to a growing interest in oil and gas theft among Mexico's organized crime groups, but also to advances in detecting siphons.

InSight Crime Analysis

In recent year, oil theft has gone from being characterized by petty theft and corruption within Pemex, to a large scale criminal operation carried out by major organized crime players, in particular the Zetas.

Since the drug cartels got involved in the trade, recorded theft has been rising quickly, and appears to be still accelerating, suggesting the multi-million dollar trade is an increasingly important source of revenue for the groups involved.

The idea that this acceleration is being fuelled by organized crime groups is supported by the geography of the trade. Of the states identified by Pemex, all but the State of Mexico have heavy drug cartel presence and the Zetas, who are behind much of the trade are believed to be present in all of them.

While oil remains the easiest fuel to steal and resell, the number of siphons targeting Pemex's natural gas pipelines shows how criminal groups have also expanded into other hydrocarbon markets.