The United States suspended consular services at its diplomatic missions in Brazil starting on Friday, citing unspecified security concerns. Officials said, "U.S. citizens seeking emergency assistance during this time should not come to the Embassy." This move comes just before Sunday’s closely fought presidential election, which remains a tense affair.

The State Department cited unspecified security concerns in announcing the unusual move. A closely fought presidential election in Brazil takes place on Sunday.

The United States announced that it was suspending consular services at its diplomatic missions in Brazil starting on Friday, citing unspecified security concerns.

"U.S. citizens seeking emergency assistance during this time should not come to the Embassy, the Consulates, or other U.S. diplomatic facilities," the announcement said.

The notice did not elaborate on the nature of the security concerns, or say how long the suspension would last. The State Department did not immediately respond to a request for comment.

Brazil is holding a first-round presidential election on Sunday in a closely fought campaign that could determine whether the country, the largest in Latin America, will follow others in the region in shifting to the political right.

Polls show that the incumbent, President Luiz Inácio Lula da Silva, a leftist, is practically tied with a right-wing challenger, Flávio Bolsonaro, the son of former President Jair Bolsonaro. A second vote is scheduled for Oct. 25.

The election comes amid a diplomatic rift with the Trump administration that has widened over the last year, with new U.S. tariffs and ideological clashes on issues like organized crime.

The United States and Brazil have a long history of jointly investigating international crimes like fraud and trafficking. Experts say the cooperation has been crucial in fighting Latin American drug gangs.

In July, the Brazilian government blocked a U.S. delegation from traveling to the country. Then, in August, the Trump administration revoked the visa of Brazil's top diplomat in the United States.

Mr. Trump has not openly championed a candidate in Sunday's elections. But some supporters of Mr. Lula say the Trump administration has in subtle ways lifted Mr. Bolsonaro, whose father lost the last election to Mr. Lula and was later convicted and placed under house arrest for plotting a coup.