Mysterious bags of ‘hazardous’ materials appeared in Mexico. Then we found more

An investigation found thousands of white bags near Monterrey, but aerial footage shows a bigger problem

• Revealed: US hazardous waste is sent to Mexico - where a toxic cocktail' of pollution emerges

Call it the mystery of the white bags. After they were found to be sprawling across acres of land near the Mexican city of Monterrey, authorities ordered their urgent" removal. Now visual evidence suggests the problem is more extensive than previously known.

An investigation by the Guardian and Quinto Elemento Lab first identified the bags in January, piling up around a factory that recycles toxic waste imported from the US. Based on this finding, Mexican authorities demanded a cleanup of what they said was 30,000 tons of stored material with hazardous characteristics".