CARACAS, Venezuela — One day after President Nicolás Maduro of Venezuela declared re-election victory, the Trump administration on Monday placed new sanctions on the crisis-ridden country, and nations across the region refused to recognize the election result.
President Trump signed an executive order on Monday afternoon imposing the new penalties, which would bar United States companies or citizens from buying debt or accounts receivable from the Venezuelan government. The order extends to Petróleos de Venezuela, the government-owned oil company that is the parent of Citgo Petroleum Corporation.
The measures were devised to close off an “avenue for corruption” that senior administration officials said they had observed Mr. Maduro and members of his government using to enrich themselves. The officials, who described the sanctions on the condition on anonymity because they were not authorized to be named discussing them, declined to reveal any specific instances.
The Lima Group, an association of mainly Latin American nations that has aimed to put pressure on Mr. Maduro’s government, issued a statement on Monday saying that it “did not recognize the legitimacy of the electoral process” and that the vote had not “met with the international standards of a democratic, free, just and transparent electoral process.”
The group includes Brazil and Colombia — Venezuela’s largest neighbors — as well as Argentina, Canada, Chile, Costa Rica, Guatemala, Honduras, Mexico, Panama, Paraguay, Peru, Guyana and Santa Lucia.
Mr. Maduro was declared the winner of Sunday’s vote, giving him a second, six-year term. Many opposition parties had been barred from running against him, and more voters abstained than cast ballots in the election, which critics had said would be rigged in the president’s favor.
The Maduro government, which used food as a powerful incentive to urge hungry Venezuelans to support him, set up tents run by government stalwarts to urge people to vote.
On Monday, Vice President Mike Pence condemned the election, denouncing Mr. Maduro’s government as a dictatorship and demanding that it allow humanitarian aid into the country.
“The illegitimate result of this fake process is a further blow to the proud democratic tradition of Venezuela,” Mr. Pence said in a statement, adding, “The United States will not sit idly by as Venezuela crumbles and the misery of their brave people continues.”
Other countries also condemned the vote.
“These were not the free and fair elections that the Venezuelan people deserve,” Germany’s Foreign Ministry wrote on Twitter, criticizing the government for trying to intimidate its opponents.
Mexico said on Monday that it had asked its ambassador to return from Venezuela to discuss the situation, and that it would reduce its relations with the country to “a minimum.”
For months, many countries had isolated Mr. Maduro’s government with threats and sanctions, warning that there would be more consequences if he held the vote. By defying them, Mr. Maduro now throws his fate more closely to Russia, Turkey, China and Iran, which have maintained ties despite his growing authoritarianism.
Days before the vote, President Recep Tayyip Erdogan of Turkey went on Venezuelan state television to voice his support for Mr. Maduro, saying, “I have faith you will be triumphant.”
Mr. Maduro presides over one of the deepest economic crises in the country’s history. Hyperinflation has cut the minimum wage to less than $2.50 a month. The country faces widespread hunger, rampant crime, a failing health system and a large-scale exodus of its citizens.
His administration has been selling off debt held by government entities, including accounts receivable, for a pittance of its worth, the United States officials said, and has pocketed the cash, leaving Venezuela’s finances in shambles.
The sanctions fall short of direct penalties on the oil sector, which the Trump administration has said would harm the Venezuelan people and American companies. They do not bar United States companies or citizens from selling oil products to or importing them from Venezuela.
Dimitris Pantoulas, a political consultant in Caracas, said the high abstention rate in the vote undercut Mr. Maduro’s legitimacy at home, “showing we could be very close to the end of this government.”
But he said the international pressure against Mr. Maduro had been blunted by the deep divisions in the opposition. Many top leaders left the country before the vote, and urged their supporters not to boycott Mr. Maduro’s chief rival, Henri Falcón, who supported much of the opposition’s political and economic agenda.
Mr. Falcón received roughly 21 percent of the vote, compared with 68 percent for Mr. Maduro, according to the official tally. Still, Mr. Maduro received fewer than six million votes, the lowest number of ballots cast for a winner in years.
Nicholas Casey reported from Caracas, and Julie Hirschfeld Davis from Washington. William Neuman contributed reporting from Caracas, and Elisabeth Malkin from Mexico City.