The death toll in Venezuela’s worst oil industry catastrophe in decades rose to 41 Sunday as firefighters continued to battle flames shooting from two burning storage tanks at the state-run Petroleros DE Venezuela (PDVSA) Amuay refinery on western Venezuela’s Caribbean coast.

The government of President Hugo Chavez declared three days of national mourning for the victims of the explosion that ripped through the huge facility in the early hours of Saturday morning. Among them were 18 members of Venezuela’s National Guard, whose barracks were located just outside Amuay’s oil storage area. Another 17 civilians were killed, including a 10-year-old child, and six bodies had yet to be identified.

The blast also leveled some 200 homes and several businesses, sending a shock-wave through nearby neighborhoods. Residents reported that they first thought the explosion was an earthquake. Evacuated in shock, many returned soon afterward for fear of looting.

Another 80 people were injured in the blast, two of whom died on Sunday. With several others still missing, the death toll is expected to rise.

It already stands as one of the worst accidents in the oil industry in recent history, surpassed only slightly by the 1997 fire at Hindustan Petroleum’s Visakhapatnam refinery in India that claimed 56 lives, and far exceeding the toll in the 2005 BP Texas City refinery blast that killed 15 workers. In Venezuela itself, it is the worst accident since 1982, when 160 people were killed in the explosion of two fuel tanks at the Ricardo Zuluaga electric power plant outside of Caracas.

Chavez, who is running for a third term as Venezuela’s president in an election slated for October 7, made a visit to the scene of the disaster on Sunday, vowing that a full investigation would be conducted into the cause of the blast.

While there, he responded angrily to a reporter who repeated statements from some of those living near the refinery, who claimed that they had smelled leaking gas in the days before the explosion.

“There is no way that there could have been a gas leak during three or four days and that no one did anything,” said Chavez.

The Venezuelan president suggested that the tragedy was being manipulated by the right-wing opposition to further their chances in the upcoming election. In particular, he insisted that charges that the accident was linked to a lack of maintenance were unfounded. “Lack of maintenance, who could possibly say this. Only someone who is irresponsible,” he said. “I recommend to all those who claim this not to speculate. This all coincides with a line of opinion being generated.”

The president added, “It would be very regrettable if some Venezuelans tried to use the pain of the victims to take advantage of the situation.”

Chavez’s chief opponent in the upcoming election, Henrique Capriles Radonski, a right-wing governor who played a prominent role in the abortive 2002 CIA-backed coup that sought Chavez’s overthrow, restricted his comments in the immediate aftermath of the disaster to statements of sympathy for the victims. Some of his political supporters and sections of the right-wing media, however, have attempted to use the blast to indict the Chavez government.

In particular, they link it to the 2003 management strike at PDVSA, when Chavez fired some 18,000 employees who had sought to paralyze the industry in a political strike aimed at bringing down the government. Capriles has vowed to rehire these former employees. The right wing also charges that the state-run oil industry has suffered because of the diversion of revenues to pay for the government’s housing and other social assistance programs.

Among Chavez’s supporters, some have speculated that the explosion could be the result of sabotage organized by the Venezuelan right and its patrons in Washington. The disaster has unfolded under conditions of mounting political tensions within Venezuela, with some indications that Washington may be preparing actions aimed at shifting the polls. Earlier this month, the Venezuelan government reported capturing a former US Marine and suspected mercenary seeking to illegally enter the country.

Venezuela ranks among the top five countries exporting oil to the United States, but it has recently sought to direct a larger share of its petroleum exports to China.

Chavez’s indictment of his right-wing opponents notwithstanding, the strongest charges of negligence and lack of maintenance have come from the unions representing oil sector workers.

Ivan Freites, a member of the executive committee of the Unitary Federation of Petroleum Workers of Venezuela, known by its Spanish acronym FUTPV, charged that his union had been warning for some time that, “there could be a problem in the refinery.”

“Investment in the industry doesn’t exist,” he said. “We have been denouncing this for the last three years.”

Speaking to Noticias24, Freites said, “Since the end of last year, we have been exposing the numerous events that have been taking place in the Paraguana refinery and the refineries throughout the country.” He said that maintenance had been delayed for months and that repairs were being made with recycled parts leaving the refineries in a “delicate situation.”

Freites demanded that the refinery be shut down until safety is assured. “The refinery has to be taken out of operation, and we have to forget about whether we are producing or whether we are going to lose the election. The lives of the people and the conditions of the workers who are living in terror must come first.”

Orlando Chirino, a former oil workers union leader who is running as the presidential candidate of the Party of Socialism and Liberty (PSL) denounced statements by the president of PDVSA and energy minister Rafael Ramirez suggesting that the blast was the result of a chance accident. He said that he and others within the unions had been warning for years that, “in the petroleum industry the accidents are the consequence of not doing periodic maintenance and of the lack of investment as well as the failure to comply with established safety protocols.” He called for an independent investigation and for the immediate dismissal of Ramirez.

Jose Bodas, the secretary of the FUTPV, described the disaster as “the chronicle of a death foretold,” using the title of a novel by Colombian author Gabriel Garcia Marquez. In an interview with the Venezuelan daily El Universal, he said that an operating emergency should be declared throughout PDVSA, and he appealed to President Chavez to allow an independent investigation.

Bodas and Chirinio, who worked at the El Palito refinery in the north-central state of Moron, jointly issued a report in 2010 on the lack of maintenance and investment in the industry, warning that they were “putting at risk the lives and health of the workers and of third parties.”

The union official said that the warnings were ignored. “The management board of PDVSA and Minister Ramirez should be sent to prison,” he said. “Workplaces cannot be turned into places of death. We demand that PDVSA invest in maintenance.”

The Amuay refinery disaster has come at a particularly bad time politically for Chavez, who has sought to boost the popularity of his government with promises to increase oil production in Venezuela, which has the largest proven crude-oil reserves of any country on the planet.

It has also served to underscore the growing tensions between his government and the Venezuelan working class, which found expression last week in a rally at which steelworkers and other industrial workers drowned out the president’s speech with demands for new contracts.