Venezuelan firefighters battled Monday to extinguish a devastating fire at the country's main oil refinery as President Hugo Chavez slammed reports that poor maintenance was to blame.

The Venezuelan leader promised an investigation into Saturday's tragedy that left 41 people dead - a gas leak is the suspected cause - and three days of national mourning were declared ahead of his trip to the Amuay refinery, in the country's far north.

But Chavez, fighting a re-election campaign ahead of October 7 polls, slammed reports that poor maintenance was responsible for the accident at the state-owned refinery, one of the biggest in the world, as he paid a visit there.

"Some philosopher said - I don't know who - that 'life must go on,'" said Chavez, describing as "irresponsible," experts who have suggested that the government had inadequate safeguards in place at the site.

He also said that those who had perished in the tragedy would not be forgotten.

"Those who died physically will resurrect spiritually with every victory of our motherland," the president assured.

The toll jumped to 41 on Sunday after two people who sustained extensive burns in the blast succumbed to their injuries.

Jesus Valdes of Coromoto Maracaibo Hospital said seven of 15 people admitted with serious injuries and still receiving care were in a "critical but stable condition."

Venezuela is South America's biggest oil producer and more than 30 hours after the worst accident ever for state oil firm Petroleos de Venezuela (PDVSA), authorities were still struggling to extinguish flames in two of nine storage tanks that were set ablaze at the refinery.

At least 18 of those killed in the fire were National Guard soldiers and 15 were civilians, most of them relatives of the troops. Six more bodies were unidentified.

Vice President Elias Jaua said "erratic winds" had complicated the work of firefighters in trying to extinguish monster flames spilling out of the tanks that could be seen from kilometers (miles away), but he insisted that the situation was "under control."

The refinery is located in a residential and commercial complex where workers live with their relatives and poor families who settled in surrounding neighborhoods.

A total of 121 people, including 48 children, were receiving medical and psychological care at a naval base, according to authorities who reported a that 209 homes and 11 businesses had been affected by the incident.

Some residents just outside the perimeter cordoned off by security forces gathered their belongings and prepared to leave their damaged homes, while others said they would remain on site.

"I have no fear," said Ali Bello, 60, as he sat in front of his home whose roof was now awkwardly sloping downward. "They are saying it won't explode again."

Venezuelan Oil Minister Rafael Ramirez predicted that production at the refinery would resume two days after the fire had been brought under control.

But Jose Bodas, general secretary of the United Federation of Oil Industry Workers, questioned these plans.

"It appears to us that it is too early to talk about resuming production without knowing the exact cause of the explosion," Bodas told AFP.

Before the blast, the Amuay refinery was able to process about 645,000 barrels of crude oil a day.

Venezuelan media have often reported complaints about safety and maintenance standards at the country's refineries, but authorities insist there were no maintenance issues at Amuay.

The Latin American nation produces about three million barrels of oil per day, according to state figures, while the Organization of the Petroleum Exporting Countries puts the number at 2.3 million barrels per day.

OPEC certified in 2011 that Venezuela has the largest oil reserves in the world at 296.5 billion barrels, surpassing Saudi Arabia, the country with the biggest refining capacity.

In March, Venezuelan authorities reported even higher reserves, of 297,570 billion.

[Image via Agence France-Presse]