Caracas, Venezuela — Half a dozen masked assailants ransacked the headquarters of Venezuela’s opposition Friday in an escalation of violence against President Nicolás Maduro’s opponents after several countries called for proof of his claim he had won the disputed presidential election.

Assailants broke down doors and hauled away valuable documents and equipment in the raid around 3 a.m., opposition leader María Corina Machado's party said. Several walls were covered in black spray paint.

The raid follows threats by top officials, including Maduro, to arrest Machado, who has gone into hiding while still urging Venezuelans and the international community to challenge Sunday’s election results.

The Biden administration has thrown its support firmly behind the opposition, recognizing candidate Edmundo González as the victor and discrediting the National Electoral Council's official results. González was tapped in April as a last-minute stand-in for Machado, who was barred from running for political office.

The U.S. announcement late Thursday followed calls from multiple governments, including Maduro's close regional allies, for Venezuela's electoral authorities to release precinct-level vote counts, as it has done during previous elections.

The electoral body declared Maduro the winner Monday, but the main opposition coalition revealed hours later that it had collected copies of more than 80% of the country's 30,000 voting tallies — printouts from the electronic voting machines — and that they show González prevailed by a more than 2-to-1 margin.

“Given the overwhelming evidence, it is clear to the United States and, most importantly, to the Venezuelan people that Edmundo González Urrutia won the most votes in Venezuela’s July 28 presidential election,” U.S. Secretary of State Antony Blinken said in a statement.

Maduro responded with a quick admonishment: “The United States needs to keep its nose out of Venezuela!”

González, whose location is also unknown, posted a message on X Friday thanking the U.S. “for recognizing the will of the Venezuelan people reflected in our electoral victory and for supporting the process of restoring democratic norms in Venezuela.”

On Friday, Venezuelan electoral authorities gave an updated vote count, but not the precinct-level tallies demanded.

National Electoral Council President Elvis Amoroso said that with 96.9% of tally sheets counted, Maduro's margin of victory was more than 8 percentage points over González: 52% to 43.2%. He attributed the delay in updating results to “massive attacks” on the “technological infrastructure.”

Blinken's announcement came amid a flurry of diplomatic efforts by Brazil, Colombia and Mexico to convince their fellow leftist to allow an impartial audit of the vote. On Thursday, the governments of the three countries issued a joint statement calling on Venezuela's electoral authorities “to move forward expeditiously and publicly release” detailed voting data.

On Friday, Vyacheslav Volodin, speaker of the lower house of Russian parliament, emphasized that Russian election monitors have witnessed Maduro's legitimate victory. He accused the U.S. of fomenting tensions in the country.

Venezuela sits atop the world’s largest proven crude reserves and once boasted Latin America’s most advanced economy, but it entered into a free fall marked by 130,000% hyperinflation and widespread shortages after Maduro took the helm in 2013. More than 7.7 million Venezuelans have fled the country since 2014, the largest exodus in Latin America’s recent history.

U.S. oil sanctions have only deepened the misery and the Biden administration — which had been easing those restrictions — is now likely to ramp them up again unless Maduro agrees to some sort of transition.

“He’s counting on being able to wait this out and people will get tired of demonstrating,” said Cynthia Arnson, a distinguished fellow at the Wilson Center, a Washington think tank. “The problem is, the country is in a death spiral and there’s no chance the economy will be able to recover without the legitimacy that comes from a fair election.”

Thousands of opposition supporters took to the streets Monday after the National Electoral Council declared Maduro the winner of the election. The government said it arrested hundreds of protesters.

On Wednesday, Maduro asked Venezuela’s highest court to conduct an audit of the election, but that request drew almost immediate criticism from foreign observers who said the court — which like most institutions is controlled by the government — lacks the independence to perform a credible review.

On Friday afternoon, González was the notable absence — an empty chair beside Maduro — when the court convened the nine presidential candidates.

Supreme Tribunal President Caryslia Rodríguez called on the candidates and their parties to provide all required documents as the court seeks to audit the results.

Maduro took the opportunity to call the absent González “the candidate of fascism” and promised to hand over all of the voting tallies.

In an op-ed published Thursday in the Wall Street Journal, Machado said she is “hiding, fearing for my life, my freedom, and that of my fellow countrymen.” She reasserted that the opposition has physical evidence that Maduro lost the election and urged the international community to intervene.

“We have voted Mr. Maduro out,” she wrote. “Now it is up to the international community to decide whether to tolerate a demonstrably illegitimate government.”

Associated Press correspondents María Verza in Mexico City and Vladimir Isachenkov in Moscow contributed.