It has been revealed that a deadly blast that killed at least 37 people at the headquarters of the Mexican state oil company Pemex was caused by a build-up of gas.
Officials say no trace of explosives was found at the site of the explosion in Mexico City.
The gas is believed to have been methane.
The explosion, last Thursday afternoon, prompted speculation about sabotage.
Mexico’s new President Enrique Pena Nieto wants a major overhaul of the company, which has been rocked by a string of safety lapses.