Firefighters have managed to extinguish one of three burning storage tanks at the country's biggest refinery, according to the Venezuelan president.
Hugo Chavez said on Tuesday the plan to restart the facility by the end of the week was still on track.
He broke the news in a series of pre-dawn tweets, saying the fire at one tank at the Amuay refinery had been put out, while the intensity of the blaze in one of the other two had fallen by 75 per cent.
"We continue battling with our heroic firefighters from [state oil company] PDVSA," he said, adding that he was talking by telephone with Rafael Ramirez, energy minister, at the scene.
Ramirez told Reuters news agency on Monday that the 645,000 barrel-per-day facility could restart operations on Friday, and that the three burning tanks would be extinguished within two days.
An explosion on Saturday at Amuay, in Venezuela's far north, killed 48 people and pushed up US fuel prices in markets that were already bullish because of a threat that Tropical Storm Isaac could disrupt refinery operations on the US Gulf Coast.
Firefighters continued to struggle on Monday to put out the blaze at the Amuay refinery, which is burning in two storage tanks and threatening to spread to nearby fuel-storage facilities.
Chavez has already ordered an investigation into the explosion and the ongoing fire, which has wounded 80 others.
A three-day period of national mourning was declared before his trip to the refinery soon after the explosion.
Chavez, running a re-election campaign in the run-up to October 7 polls, criticised 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 on Sunday.
"Some philosopher said, I don't know who, that 'life must go on'," Chavez said, describing as "irresponsible" experts who have suggested that the government had inadequate safeguards in place at the site.
Ramirez, the energy minister, said the explosion was triggered by a gas leak, the cause of which remained to be determined.
"The gas cloud exploded, igniting at least two storage tanks and other facilities at the refinery," he told state-controlled VTV television.
Ramirez said the explosion was powerful and caused "significant damage" not only to the plant, but also to nearby shops and homes.
Firefighters were able to bring the fire under control, though smoke was still billowing from the facility.
International oil prices have risen as a result of the fire, and investment bank Goldman Sachs noted on Monday that similar major fires "typically [have] caused months in delays".
Ramirez said he expected production of the 645,000-barrels-per-day facility, which makes up two-thirds of the world's second largest refinery complex, to resume within two days.
As far as fuel shipments, he said, "we won't have major effects".
He said nine storage tanks were damaged and that oil workers as well as troops inspecting the damage would determine the cause of the gas leak.
Amuay is part of the Paraguana Refinery Complex, which also includes the adjacent Cardon refinery.
Together, the two refineries process about 900,000 barrels of crude a day and 200,000 barrels of petrol. Venezuela is a major supplier of oil to the US and a member of the OPEC.
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 largest refining capacity.