TLAHUELILPAN/MEXICO CITY, Mexico (Reuters) - Mexico’s new government knew a pipeline was leaking but did not act for hours before a blast killed at least 85 people, a minister said on Sunday, increasing scrutiny of a push to stop fuel theft seen as the president’s first crackdown on crime.

State oil firm Pemex did not close the gasoline pipe when first notified by the military, about four hours before Friday’s blast, because it considered the leak “minimal,” Security Minister Alfonso Durazo told a news conference.

In the hours that followed, the leak grew and as many as 800 people brought plastic containers to the gushing duct, filling up with free fuel in what witnesses described as an almost festive atmosphere.

Relatives of some of the victims said fuel shortages stemming from President Andres Manuel Lopez Obrador’s plan attracted people to the leak at the Tula-Tuxpan pipeline, a few miles from a major refinery.

In December, Lopez Obrador sent soldiers to refineries to help fight organized crime and white-collar fuel theft, while shutting down pipelines tapped by thieves. The measures have reduced theft, but in early January also led to shortages and lines at gas stations stretching for miles.

Soon after dark on Friday in the Tlahuelilpan district of the central Hidalgo state, gasoline and fumes ignited in a fireball that killed at least 85 people and left a black scar on the land. Dozens were so badly charred they will only be identified through DNA testing, officials said.

Critics say the government did too little to prevent people from gathering at the scene before the explosion, was too hasty in sending gasoline through the duct after weeks of it being closed due to the fuel theft crackdown and acted too slowly once the leak was detected.

DESPERATE

Half a dozen people told Reuters their relatives went to the leaking duct because they had been struggling to find fuel and were desperate to fill up cars to get to work or run their farms.

“A lot of innocent people came here, perhaps their car didn’t have enough gasoline for tomorrow, and they said: ‘I’m just going to go for a few liters’,” said farmer Isidoro Velasco, 51, who said his nephew, Mario Hidalgo, was probably killed.

Pemex had been in a rush to reopen the pipeline to avoid a new round of gasoline shortages in Mexico City, said Gonzalo Monroy, the head of Mexico-based energy consulting firm GMEC, citing conversations with oil industry professionals.

Disputing accounts that fuel thieves opened up the pipe, he said sources in Pemex indicated the fissure occurred at a spot Pemex had previously repaired, and gave way under the pressure of a new surge of fuel.

Pemex officials decided to keep fuel running after the first signs of a leak, and send a team to inspect it, he said.

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Pemex did not respond to requests for comment.

When questioned about why it took so long to close the pipe’s valves after the leak was detected, Durazo said Pemex followed protocol. The explosion occurred half an hour after Pemex closed the valve, he said, because high-octane gasoline remained in the pipe.

Lopez Obrador said on Sunday that the disaster had not weakened his resolve to fight fuel theft.

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“I won’t take a single step backwards,” he said at the first of two news conferences. “I can only offer people apologies, if this action causes sacrifices, harm and inconveniences.”

Lopez Obrador said he hoped supply would normalize soon as Mexico buys more tanker trucks for distribution by road.

If successful in uprooting a parallel fuel network that siphons off about $3 billion worth of fuel from Pemex each year, the veteran leftist who won last year’s election on promises to root out endemic corruption will have scored a big early victory, strengthening ailing national oil company Pemex and helping stabilize fuel prices.

The blast, however, has raised the stakes.

Failure would likely not only erode his popularity but pose risks for the economy, the world’s sixth-biggest fuel market.

An opinion poll last week showed the fuel strategy was a polarizing issue, with about half the population supporting the measure despite the lines at gas stations and other difficulties.

REPEAT ATTACKS

Pemex initially took the Tula-Tuxpan pipeline out of service in late December as the government tried to protect it from gangs who had hit it 10 times in Tlahuelilpan, Pemex Chief Executive Officer Octavio Romero said on Saturday.

After Pemex began attempting to restart operations on Wednesday, the line experienced four more attacks.

Romero said Pemex closed a valve at the pipeline on Friday after noting a drop in pressure from the leak. Pemex informed other authorities of the leak at 4:50 p.m., he added.

Responding to questions about why fuel kept flowing from the leak up until the explosion, Lopez Obrador said that 10,000 barrels of gasoline were accumulated in the pipeline between the Tula refinery and the village. Energy Minister Rocio Nahle said the pipeline was pressurized.

Lopez Obrador said the army, which deployed just 25 soldiers before the explosion, gave orders for villagers to stay back, but were ignored.