Moscow ? Chechen warlord Shamil Basayev claimed responsibility for a power outage that caused chaos in Moscow, plunging entire neighborhoods into darkness and stranding thousands of subway passengers, a rebel-linked Web site said Friday.

Russian officials insist worn-out equipment caused the power failure, which began with an explosion and fire at a 40-year-old substation and affected the Russian capital and surrounding region. But Basayev has a history of striking at new and spectacular targets in his terrorist campaign.

“Our sabotage units delivered a major blow to one of the most important life-support systems of the Russian empire,” the Kavkazcenter Web site quoted the Chechen rebel leader as saying in an e-mail.

The Federal Security Service, or FSB, declined comment on the claim, and telephone calls to the Industry and Energy Ministry were not answered.

But Industry and Energy Minister Viktor Khristenko was quoted earlier in the day as rejecting speculation that a terrorist act was responsible for Wednesday’s blackout.

“I think that this is not a terrorist act. We are just using old equipment, from 1958, which needs to be replaced,” Khristenko told the RIA-Novosti news agency, the Gazeta.ru news Web site reported.

The conflicting claims recalled the aftermath of the blackout in eight U.S. states and Canada in August 2003. Although a shadowy group calling itself the Abu Hafs al-Masri Brigades claimed responsibility, investigators quickly ruled out any sabotage.

Basayev is Russia’s most wanted man, and is seen as the driving force behind the decade-old insurgency in the breakaway republic of Chechnya since Russian security forces killed guerrilla leader Aslan Maskhadov on March 8.

Police officers speak to passengers in a Moscow subway closed due to a power outage. Electrical outages hit large sections of the Russian capital and nearby regions this week, forcing many subway lines and trolleys to halt service while frustrated pedestrians tried to flag down taxis on traffic-jammed streets. On Friday Chechen warlord Shamil Basayev claimed responsibility for the outage.

Basayev has claimed responsibility for many of Russia’s most grisly terrorist attacks, including the 2002 Moscow theater hostage-taking and last September’s school siege in southern Russia, in which more than 330 people died – half of them children.

The blackout happened during an unseasonable heat wave. The shutdown of subways and trolley buses forced thousands of people to reach their destinations on foot, jamming sidewalks.

The head of the nation’s electricity monopoly, Anatoly Chubais, has borne the brunt of criticism for the power outage.