Jaua said in a message on Twitter that a third tank had just ignited at the Amuay refinery. The refinery has been in flames since Saturday, and officials had previously said they hoped to blaze to keep diminishing until it could be extinguished.
Falcon state Gov. Stella Lugo told the Venezuelan radio station Union Radio that the death toll had risen to 48, but later said the correct number was 41 and that some victims' names had been mistakenly included twice on a list.
About 150 people were injured in the disaster, 33 of whom remain in hospitals, Prosecutor General Luisa Ortega said at a news conference at the refinery complex. "We still don't have facts to determine the causes of the accident," she said.
Criticisms of the government's response have emerged from local residents as well as oil experts. People in neighborhoods next to the refinery said they had no official warning before the explosion hit at about 1 a.m. on Saturday.
"What bothers us is that there was no sign of an alarm. I would have liked for an alarm to have gone off or something," said Luis Suarez, a bank employee in the neighborhood. "Many of us woke up thinking it was an earthquake."
The blast knocked down walls, shattered windows and left streets littered with rubble.
People who live next to the refinery said they smelled strong fumes coming from the refinery starting between 7 p.m. and 8 p.m. Friday, hours before the blast, but many said they weren't worried because they had smelled such odors before.
Then, a cloud of gas ignited in an area with fuel storage tanks and exploded. Some of the first tanks to catch fire still billowed smoke on Monday.
President Hugo Chavez visited the refinery on Sunday. In a televised conversation with the president, one state oil company official said workers had made their rounds after 9 p.m. and hadn't noticed anything unusual. The official said that at about midnight officials detected the gas leak and "went out to the street to block traffic."
"And later something happened that set (it) off," Chavez said. "A spark somewhere."
Energy analyst Jorge Pinon said the accounts of the hours leading up the explosion raise concerns.
"The fact that the gas leak went undetected for a number of hours and that there was no evacuation alarm (or) order indicates to me that there is a lack of safety related planning and behaviors throughout the complex, and most important in nearby communities," Pinon said.
"The key to refinery safety is not only equipment and maintenance but processes and behaviors," Pinon added, "not only within company employees but also contractors and surrounding communities."
Amuay is among the world's largest refineries and is part of the Paraguana Refining Center, which also includes the adjacent Cardon refinery. Together, the refineries process about 900,000 barrels of crude per day and 200,000 barrels of gasoline.
The disaster occurred little more than a month before Venezuela's upcoming Oct. 7 presidential election. Opposition candidate Henrique Capriles said the disaster shouldn't be politicized but repeated past criticisms about the number of accidents at the state-owned oil company.
"Accidents occur for a reason, and we Venezuelans are expecting there to be a conclusive response, a serious, responsible and transparent investigation, in order to see what the situation was," Capriles said at a news conference.
Capriles has previously been critical of problems in the oil industry.
"Look at how many events have occurred, how many accidents, how many workers have lost their lives," Capriles said. He criticized state oil company president Rafael Ramirez for what he called "political maneuvering," saying what's needed is a serious investigation.