(Adds end to public holidays)

By Mariela Nava and Brian Ellsworth

CARACAS/MARACAIBO, Venezuela, March 13 (Reuters) - President Nicolas Maduro's government scrambled on Wednesday to return power to western Venezuela following heavy looting in the country's second largest city, while China offered to help the OPEC-member nation end its worst blackout on record.

Power had returned to many parts of Venezuela after a nationwide outage last week, with the country's main port terminal of Jose, which is crucial for oil exports, resuming operations. The government said people could return to work on Thursday, following several consecutive public holidays due to the lack of electricity.

School will remain suspended for 24 more hours, Information Minister Jorge Rodriguez said in a state television broadcast on Wednesday, adding that power supply had been broadly restored but problems remained in some areas with transformers that had been "sabotaged."

The ruling Socialist Party blamed the outage on U.S. sabotage, accusing President Donald Trump of being responsible for several cyber attacks on Venezuela's main dam.

Energy supplies remained patchy in the sweltering western state of Zulia, where anger after nearly a week without power overflowed into street violence.

Looters smashed shop windows and made off with merchandise in more than 300 businesses across the state along the border with Colombia, the Zulia chapter of business organization Fedecamaras said in a statement.

"About 100 people came into the store and took all the food, the point of sale terminals," said Maria Centeno, 29, the owner of a store selling food and furniture that was looted on Sunday. "They were people from the community. The police came by and they told me to sort it out myself."

Following the wave of pillaging on Sunday, many businesses sold off their remaining merchandise on the cheap for fear of more looting.

The country's top food company, Empresas Polar, said four facilities in Maracaibo, Venezuela's biggest city after Caracas, had been sacked this week, with looters making off with water, soft drinks and pasta.

The Information Ministry did not immediately respond to a request for comment.

In Maracaibo, once known for flashy displays of oil wealth, people bought food at the few business that remained open. Gasoline lines stretched for blocks.

"In my house I have one kilo of rice and one kilo of lentils," said Jose Navas, 53, a security guard. "That's what I'll eat today. What will I eat tomorrow? This is really bad."

CHINA SUPPORT

Venezuela, which has long suffered from high crime rates and shortages of basic goods, plunged into a deep political crisis in January when Juan Guaido, head of the opposition-controlled congress, invoked the constitution to assume an interim presidency, arguing Maduro's 2018 re-election was not legitimate.

The move has put Venezuela at the heart of a geopolitical tussle, with the United States leading most Western nations in recognizing Guaido as the legitimate head of state, while Russia, China and others support Maduro.

The United States is preparing to withdraw its remaining diplomats from Venezuela, an effort that will not involve the U.S. military, after Maduro on Tuesday ordered them to leave within 72 hours.

China on Wednesday offered to provide help and technical support to restore electricity, and backed Maduro's assertion that the problem was the result of sabotage.

Maduro's critics have insisted that rampant corruption and a decade of incompetent management by state authorities were to blame.

A technical problem with transmission lines linking the Guri hydroelectric plant in southeastern Venezuela to the national power grid likely caused the blackout, former energy company officials and local engineers have told Reuters.

Despite the resumption of shipments from Jose, Venezuela's oil industry is struggling with the impact of U.S. sanctions on state oil company Petróleos de Venezuela, S.A., or PDVSA . Two storage tanks exploded at the Petro San Felix heavy-crude upgrading project on Wednesday, sources said.

With Maduro still in control of state functions and retaining the loyalty of the armed forces, Norway's foreign ministry said on Wednesday it would be prepared to act as a mediator or facilitator of talks between the government and opposition.

"We are in contact with both sides in Venezuela and can contribute if they so wish," said a Norwegian foreign ministry spokeswoman.

The Nordic nation, which has not recognized Guaido as the president, has a long history of brokering peace processes worldwide, most recently when it helped seal a 2016 deal between the government of Colombia and Marxist FARC rebels.

But dialogue with Maduro is a nonstarter for many opponents, who accuse him of using previous negotiations to buy time and divide the opposition.

"Our position is the same: the conditions are not ripe for mediation or dialogue," said opposition legislator Fernando Sucre, adding that there had not been talks with Norway. "The agony of the Venezuelan people has increased because of the electricity disaster, and it cannot keep being extended." (Reporting by Mariela Nava, Brian Ellsworth and Vivian Sequera; additional reporting by Gwladys Fouche in Oslo Editing by Daniel Flynn, Leslie Adler, Rosalba O'Brien and Richard Chang)

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