Power was fully back online for residents of Brazil's south, southeast and midwest regions mid-morning on Tuesday, while it continued to return gradually in northern regions, after an "incident" caused outages across the nation.
In Brazil's north and northeast, power was still being restored before 10:30 am local time (1330 GMT), the mines and energy ministry said in a statement.
Some 16,000 megawatts of power was brought down after an "incident," which was still being looked into, it said.
Mines and Energy Minister Alexandre Silveira has "ordered an investigation into the causes of the incident," the ministry added.
Private power firms operating in Brazil were affected by the outages.
Equatorial Energia and Enel Brasil said they were gradually resuming power supply to their clients, while CPFL Energia said supply had already resumed for all customers.


Mediator Pakistan says US, Iran expected to sign initial deal within 24 hours
India Air Force plane crash kills all five onboard
Trump says US military strike killed leader of Venezuela's Tren de Aragua gang
Qatar rejects media report on energy production decisions
Trump says Iran war deal close as Strait of Hormuz tensions linger
Victims' families mark Air India crash anniversary with prayers and tributes
Ebola outbreak spreads to crowded displacement camp in Congo
Fire breaks out at New Zealand's Wellington airport, disrupting flights
