By Daniel Wallis and Deisy Buitrago

CARACAS (Reuters) - Venezuelan President Nicolas Maduro said on Tuesday he had proof that a massive power outage was caused by saboteurs aiming to throw the country into chaos before municipal elections this weekend.

The blackout on Monday night was the second major power outage the year, plunging much of the country into darkness and prompting accusations of government incompetence from the opposition.

Speaking on state TV alongside Electricity Minister Jesse Chacon and other officials, Maduro briefly showed a photo of what appeared to be a cut conductor cable lying on the floor.

"What motive could there be for leaving a whole country without electricity?" he said, adding that Chacon had brought him the evidence and more details would be unveiled on Wednesday.

"We always face these attacks by the right-wing fascists ... they wanted to make me, as president of the republic, decree a state of emergency and suspend the elections."

Critics of the government say lack of maintenance was likely to blame for the outage.

Maduro said power had been restored in record time and praised the workers involved.

"Whoever made this criminal attack wanted to leave our Venezuela without electricity for 24 to 48 hours ... thinking that would convince people not to continue with the revolution."

Maduro's combative rhetoric echoed his allegations in September, when he also accused the opposition of sabotaging the national grid to discredit him after a blackout that was one of the worst in the OPEC nation's history.

Venezuela has experienced periodic power cuts since 2009, although the capital, Caracas, had been spared the worst of the outages, but it was hit by Monday night's blackout, which cut electricity across about half the country.

Nationwide municipal elections on Sunday are seen as a test of Maduro's political strength after he narrowly won the presidency in April to replace his late mentor, Hugo Chavez.

Since coming to power, Maduro has accused the opposition of plotting to assassinate him, and more recently of trying to undermine his government and wreck the economy through price-gouging and the hoarding of consumer goods.

Critics say the electricity problems symbolize the failure of 15 years of socialist rule in Venezuela, a country of 29 million people with the biggest oil reserves in the world.

(Reporting by Daniel Wallis and Deisy Buitrago; editing by Christopher Wilson)