November 11 - Brazil's President Luiz Inacio Lula da Silva today demanded an explanation for the blackout which left large parts of the country, including Rio de Janeiro, the host city for the 2016 Olympics and Paralympics, in darkness and chaos for more than five hours after the country's worst power outrage in a decade.
The blackout last night left tens of millions of people without power.
Lula summoned his Energy Minister, Edison Lobao, for an urgent meeting in the capital Brasilia early today to explain what caused the outage.
Initial findings showed the outage was triggered when a major storm downed three power lines that run from the giant Itaipu hydroelectric dam on Brazil's border with Paraguay.
Marcio Zimmerman, the Energy Ministry's Executive Secretary, said: "The system is designed to withstand two contingencies - here we had three."
But the Itaipu Binacional company that runs the plant said in a statement on Wednesday the problem originated elsewhere.
It said the dam, which supplies about 20 per cent of Brazil's energy and 90 per cent of Paraguay's, had been functioning normally but had not been able to transmit energy because power lines were not working.
Many tourists in Rio left their hotel rooms along Copacabana beach because of the lack of air-conditioning and milled around on the darkened streets.
Rio State Governor Sergio Cabral sent an elite police unit into the streets early today to help maintain calm in a city known for its high crime rate.
Rio's Mayor Eduardo Paes also dispatched 300 extra-unarmed civil guards to help control traffic, which was chaos.
Vanderlei Macris, a spokesman from the opposition Social Democracy Party, said: "We can't discuss growth plans if we're facing electricity disruptions.
"Brazil has announced huge investments like building a bullet train and hosting the World Cup and Olympics.
"It seems the country isn't prepared enough for investments of this magnitude."
The blackout affected 18 of Brazil's 26 states, including the capital Brasilia, and left all of Paraguay in the dark for about 15 minutes.
Paraguay's state electricity company said that the problem originated in Brazilian power lines.
Adriano Pires, director of the Brazilian Center for Infrastructure Studies, claimed that not be surprised by the problem.
He said: "The very long transmission lines in Brazil are very badly maintained,"
"This shows that Brazil is very vulnerable.
"You can't leave a country the size of Brazil hostage to accidents."