A blackout that cast half of Brazil into the dark overnight was caused by a fierce storm that shorted three high-tension transmission lines, the energy ministry said on Wednesday.
But contradictory statements came from an electricity operator responsible for the affected area, and from the state electricity company in neighboring Paraguay.
An "atmospheric discharge" packing heavy winds, rain and lightning knocked out the lines running from the country's biggest power plant, the Itaipu hydroelectric facility on the border with Paraguay, Energy Minister Edison Lobao told a news conference.
A domino effect meant 40 percent of the national energy supply went offline overnight, he said.
He was flanked by aides and operators of Brazil's electricity grid who had held emergency discussions to determine the reason of the outage, which plunged 70 million people -- more than a third of Brazil's population of 190 million -- into blackness.
"We all arrived at the conclusion that what happened was the result of atmospheric discharges, very strong rain and wind," he told the televised news conference.
"Everything is completely working now," he said.
His executive secretary, Marcio Zimmermann, said the southern half of Brazil suffered an "average" three hours without power -- some parts had energy restored within minutes, others took several hours.
The explanation contradicted an earlier statement by Furnas, Brazil's state-owned electricity company responsible for the affected area, which said no damage had been found to any of Itaipu's transmission lines.
The state electricity company of Paraguay, which also suffered a 30-minute blackout across its entire small territory during the emergency, was also skeptical weather was at fault, but confirmed that three transmission lines were at the source of the problem.