THE recent blackouts in several Brazilian cities were caused by human error rather than natural occurrences such as lightning, President Dilma Rousseff said yesterday.

"When somebody tells you that the system fell because of lightning, laugh. Lighting falls everyday in this country. It cannot turn off the system. If it does, it is human error," Rousseff told reporters.

Several cities, including parts of Rio, were plunged into darkness and unbearable heat on Wednesday, when a blackout occurred.

Rousseff blamed the incident on lack of maintenance, saying "the old air-conditioning system should have been replaced."

Among frequent blackouts across the country, "there were six large incidents over the past few months," the president said. But she dismissed the speculation of another energy crisis as "ridiculous."

The nation was under energy rationing a decade ago when the majority of Brazilians had to reduce energy consumption at home to avoid high fines.