By Brian Ellsworth and Patricia Velez

CARACAS (Reuters) - A blackout cut power to much of Venezuela on Friday, snarling traffic in the capital Caracas and other major cities as authorities scrambled to restore electricity after the outage, which twice interrupted a presidential broadcast.

Pedestrians streamed into the streets of Caracas as the blackout shuttered the underground metro trains and left frustrated drivers honking in the chaos without stoplights.

Government ministers in the late afternoon said they expected power would be restored shortly. It was the second nationwide major electricity outage in less than a year.

"How am I going to get to my house? By the grace of God," said Pedro Mayora, 58, an accountant who was waiting outside the Metro to see how he would reach his home on the poor west end of the city.

Workers stood in groups outside evacuated buildings, some complaining of difficulty in communicating over congested cellular phone lines.

An outage at a power station in the center of the country led to other generation centers going offline, halting service in that region and in the Andes region in the west, Electricity Minister Jesse Chacon told state television.

The problems extended to Maracaibo, Venezuela's second city, and the industrial center of Valencia.

The OPEC nation has suffered an increasing number of power outages in recent years, which critics have attributed to low electricity tariffs and limited state investment following the 2007 nationalization of the power sector.

Television screens froze for several seconds as Maduro was speaking during a broadcast of the awards ceremony for a national journalism prize. The words "It looks like the power went out" were audible in the background.

"Traffic normally flows fine, but with the power out it's complete chaos," said Carlos Pena, 58, a fuel station worker.

A representative of state oil company PDVSA said there were no reports of the oil industry being affected.

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President Nicolas Maduro in December blamed a similar power outage on opposition saboteurs who attacked a transmission line with a firearm.

Critics call the power problems a symptom of 15 years of socialist policies that have left the country without a steady supply of energy despite having the world's largest oil reserves.

Late socialist leader Hugo Chavez in 2007 nationalized the country's power sector as part of a broad wave of state takeovers.

Maduro this year weathered three months of often violent opposition demonstrations demanding his resignation that were in part motivated by complaints over shoddy public services. He said the protests were a U.S.-backed attempt to overthrow him.

(Reporting by Caracas newsroom; Editing by James Dalgleish and Mohammad Zargham)