Exactly two weeks after New York went powerless, London on Thursday was hit by a major power failure affecting up to 500,000 people.

Commuter traffic was severely hit and officials said close to 250,000 commuters, who use the public transportation system, could be stranded.

"There will be travellers underground. I don't know the extent of (the disturbance) yet. It's at the end of rush hour, the peak period, so it's a busy time," a spokesman for the London Underground told a news agency.

London Mayor Ken Livingstone ruled out a terrorist angle into the outage. He, however, called the blackout a 'disgrace' and said his office would begin a probe immediately.

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A couple of days after the New York power outage, some reports said the Al Qaeda had claimed responsibility.

"We have lost supplies to large parts of south London in the last few minutes as a result of a National Grid failure supply in the south London area," a spokesman for EDF Energy, which supplies power to the London area, said.

"It's difficult to predict how long this is going to take. National Grid has got to get the circuit back," he added.

Approximately an hour after the power failure, which occurred at 2245 IST, lights were gradually coming back on in the British capital.

Agencies