CARACAS, Venezuela — Venezuelan authorities moved to prohibit opposition leader and self-declared interim president Juan Guaidó from leaving the country and to freeze his bank accounts, prompting the United States, which a day earlier slapped sweeping sanctions on Venezuela’s state-run oil company, to say there would be “serious consequences” if Guaidó is harmed.

Embattled President Nicolás Maduro then followed up by saying he was ready for a dialogue with the Guaidó-led opposition in an interview with Russia’s RIA news agency released Wednesday.

“I am ready to sit down at the negotiating table with the opposition so that we could talk about what benefits Venezuela,” said Maduro, adding that letters had been sent to the governments of Mexico, Uruguay, Bolivia, Russia, the Vatican and other European countries to involve them in the process.

Secretary of State Mike Pompeo told the U.N. Security Council Jan. 26 that it is "time for every other nation to pick a side” on Venezuela's leadership. (Reuters)

Russia praised Maduro’s willingness to negotiate with the U.S.-backed opposition, the Kremlin said on Wednesday. “The fact that President Maduro is open to dialogue with the opposition deserves high praise and is commendable,” spokesman Dmitry Peskov told reporters in a phone call.

Despite the offer, authorities ratcheted up pressure on the opposition with a request by the chief prosecutor to freeze Guaidó’s assets, which was later ratified by the loyalist Supreme Court as a preventive measure pending a full investigation. The move stopped short of a detention order — something the Trump administration has strongly warned against.

“We request these preventive measures against Guaidó while we compile elements to stop the events that since January 22 have broken the peace of the republic,” the prosecutor, Tarek Saab, said in a news conference.

Venezuelans living in the U.S. gathered Jan. 23 in cities across the country to protest against Nicolás Maduro and back opposition leader Juan Guaidó. (The Washington Post)

Speaking at the opposition-led National Assembly, which he heads, Guaidó responded to the move by dismissing it as “nothing new under the sun.” He said it came from “a regime that doesn’t give answers to Venezuelans” and whose “only answer is persecution and repression.” Guaidó added: “The world is clear on what’s happening in Venezuela . . . Let’s not desist because of threats and persecution.”

The United States, which backs Guaidó as the legitimate leader of Venezuela, pushed back hard against the chief prosecutor’s effort. “We denounce the illegitimate former Venezuelan Attorney General’s threats against President Juan Guaidó,” White House national security adviser John Bolton wrote on Twitter. “Let me reiterate—there will be serious consequences for those who attempt to subvert democracy and harm Guaido.”

The chief prosecutor’s request came after the United States escalated its efforts to unseat the leftist Maduro on Monday by punishing the state oil company, Petróleos de Venezuela S.A. (PDVSA), in an effort to transfer its control to the opposition. The U.S. move freezes $7 billion in U.S.-based assets and blocks more than $11 billion in revenue that Venezuela would get from oil sales next year through its U.S.-based company Citgo, which owns three refineries in the United States and employs thousands of workers.

In his interview Wednesday with Russian media, Maduro said the decision violated international law and called it one of Bolton’s “most insane” decisions.

“It is an unlawful decision in a bid to expropriate a Venezuelan asset, a Venezuelan company,” he said. “I am confident that we will emerge victorious, protecting the company Citgo as the property of the Venezuelan people.”

The Treasury Department said money would go to a fund that a transitional government headed by Guaidó could eventually access.

PDVSA chief Manuel Quevedo suggested Tuesday that Venezuela might withhold sales to the United States, where it is no longer guaranteed payment after the sanctions.

“For a tanker to leave a Venezuelan port with the crude that belongs to our people, it has to be paid for before leaving the port,” he said.

On Tuesday, Secretary of State Mike Pompeo also gave Guaidó control over certain Venezuelan government accounts at the Federal Reserve Bank of New York.

Revenue from oil sales to the United States and from Citgo, which imports Venezuela’s heavy crude oil, refines it and distributes gasoline throughout the United States, is one of the Maduro administration’s main sources of income. These sanctions, experts say, constitute the biggest setbackthat the populist Maduro has ever confronted.

“This is not just a big blow to Maduro, but also to the Venezuelan people,” said Henkel Garcia, head of local consulting firm Econometrica. “It will hit the population hard in the short term with scarcity of food and medicines and even of gasoline.”

Venezuela’s government is responsible for more than half the country’s imports of food and medicine. The country also depends on imports of raw materials to manufacture and distribute basic goods.

The sanctions come during a tense week in Venezuela. Overnight protests are surging and are being met with harsh repression. At least 35 people have been killed and more than 800 detained in a week. More protest marches are scheduled this week.

Many Venezuelans are desperate for change as they confront crippling hyperinflation and scarcity of vital medicines, but many worry that U.S. sanctions could make the dramatic situation even worse in the short term.

Amaury Caraballo, 62, a businessman, said that he has been trying to buy more food but that prices are too high to accumulate much. “I support the sanctions because it’s the only way to pressure the regime,” he said. “Everyone in the country is struggling to find food and medicines already. I’m definitely worried the sanctions will harden the situation for us, and I’m getting prepared for it, but I think it will be a good thing in the long term.”

A 63-year-old textile businessman, Jacobo Benzaken, said the sanctions would hit the people harder than they would hit the government. “I’m scared of not having transportation, food,” he said. “Everything is scary. If we’re not doing well now, imagine what comes next?”

In Washington, speculation about possible U.S. military intervention grew Monday after Bolton appeared at a news conference carrying a yellow notepad bearing the handwritten words, “5,000 troops to Colombia.”

Speaking to soldiers before military exercises near Caracas, Maduro seized on the notepad to assert that the United States was staging a coup against him.

“It’s an infantile way of leading an imperialist foreign policy,” Maduro said. “You, military leaders of our homeland have to stay loyal and subordinate, and defend us saying ‘Yankee go home, get out of here.’ ”

Acting defense secretary Patrick Shanahan said Tuesday that he has not spoken with Bolton about the possibility of deploying 5,000 troops to Colombia. He declined to comment on whether he had spoken to anyone else in the administration about the possible involvement of American troops.

Shanahan said the National Security Council, under Bolton’s leadership, has “created a number of options” with regard to Venezuela.

Krygier reported from Miami and Faiola from Sao Paulo, Brazil. Paul Sonne in Washington and Paul Schemm contributed to this report.