Brazilian officials are disputing the claim by “60 Minutes” and others that a blackout in 2007 was caused by computer hackers. Wired magazine’s blog Threat Level, citing government and investigative sources, reports that the outage “was actually the result of a utility company’s negligent maintenance of high voltage insulators on two transmission lines.” Insulators hang from power lines and are prone to collect debris, which can cause power surges. In this case, officials say soot from nearby fires collected on the insulators.

Threat Level, which has long been skeptical of some of the more extraordinary claims by U.S. officials about cyber threats to critical infrastructure, spoke to the utility company involved in the blackout and got a denial of any hacker involvement. The company “has no knowledge of hackers acting in [the] power transmission system,” TL reported.

News of the “60 Minutes” piece hit the wires on Saturday, and over the weekend, Brazilian government officials started batting down the story. A senior homeland security official in Brazil told newspaper Folha de S. Paulo that he had investigated the allegations of a hacker causing the blackout and found no traces. Read the full story