The fire was started by a lightning bolt during a storm Wednesday night, but the 146,000 barrel-per-day (bpd) El Palito facility continued operating. Two tanks were initially set alight, but the fire in one was put out within hours.

In a statement, PDVSA said the blaze in the second storage tank was completely extinguished late on Friday. No one was hurt in Wednesday night's lightning strike.

The second refinery accident in a month has increased concerns about state oil company PDVSA's safety record and practices ahead of an Oct. 7 presidential election.

In August, PDVSA halted almost all output at the country's biggest refinery, Amuay, for six days after a gas leak caused an explosion that killed 42 people.

PDVSA has suffered a string of accidents, outages and unplanned stoppages for maintenance across its refinery network in recent years, hurting the OPEC nation's vital fuel exports.