Late last month, President Andres Manuel Lopez Obrador launched a program to shut down an illegal fuel distribution network that siphons off about $3 billion worth of fuel annually from state oil firm Pemex.
The Obrador administration closed key pipelines in an effort to crack down on fuel theft, which the Mexican leader said cost the country an estimated $3 billion previous year.
"These pipelines haven't been changed in more than 30 years, with thousands of illegal taps, patched-up pipelines without the capacity to carry fuel", he said Monday.
"I urge the entire population not to be complicit in fuel theft", Mr Fayad posted (in Spanish).
Mexico is regularly rocked by deadly explosions at illegal pipeline taps, a unsafe but lucrative business whose players include powerful drug cartels and corrupt Pemex insiders. Bodies were so badly charred they will only be identified through DNA testing, officials said.
The anti-theft operation, which he launched on December 20, had led to shortages and long queues at petrol stations.
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He urged people not to steal fuel, as it could put their lives at risk. He said he plans to increase shipments of tanker trucks and financial aid to areas affected by fuel shortages. The explosion was half an hour after Pemex closed the valve, he said, because high-octane petrol was still in the pipe.
Pemex Chief Executive Octavio Romero said his team had followed protocol, though he would not confirm or deny if there was negligence or corruption related to the delay in closing the pipeline.
Initial reports had said that at least 21 died in the blast.
Lopez Obrador, who vowed to continue the crackdown on theft, defended the army in the face of questions about why soldiers failed to prevent the tragedy.
"A lot of people arrived with their jerrycans because of the gasoline shortages we've had", said Martin Trejo, 55, who was searching for his son, one of those who had gone to collect the leaking fuel.
Fuel spurted from the pipeline for around two hours after Pemex alerted other authorities to the leak, with no visible loss of pressure, before the explosion.
Lopez Obrador said the disaster had hardened his resolve to fight fuel theft and the government was looking at ways to strengthen ageing pipelines to make it harder to illegally suck fuel from them.