Washington, Feb 22 (IANS): Hacker group Anonymous within the next year or two could bring about a limited power outage in the US through a cyber attack, a top official has said.

The group has earlier taken down the websites of the Central Intelligence Agency (CIA), the Federal Bureau of Investigation (FBI) and the Department of Justice, Xinhua reported.

Keith Alexander, director of the National Security Agency (NSA) warned in meetings at the White House and in other private sessions that Anonymous could have the ability to bring about a power outage, said the Wall Street Journal.

Alexander did not publicly express concern about the potential of Anonymous to disrupt power supply, but warned that cyber attackers could disable or even damage computer networks.

The Wall Street Journal said any attack by Anonymous directed at the power grid was likely to inflict limited damage, but would be certain to create alarm, especially if Anonymous took credit publicly.

Grid officials said their systems face regular attacks, and that they devote tremendous resources to repelling invaders.

Officials explained that the electric grid has a number of backup systems that allow utilities to restore power quickly if it is taken down in a cyber attack.