Adams, a Democrat who would become the first of the city's 110 mayors to be criminally charged while in office, said in a video statement that if charges were filed they would be "entirely false, based on lies." He vowed to remain in office while fighting them.

"If I'm charged, I know I'm innocent. I will request an immediate trial so New Yorkers can hear the truth," Adams said.

Defying calls from Democratic politicians for him to resign, he said: "You elected me to lead this city, and lead it I will."

The indictment was likely to be unsealed on Thursday when Adams may appear in court, the Times reported. In the meantime the exact charges remained uncertain. It also remained unclear whether Adams would be arrested or voluntarily surrender.

Other media later reported that a federal grand jury had indicted Adams, citing unnamed sources.

The charges come after the FBI last November searched Adams' electronic devices, and in the wake of a slew of resignations by top city officials in recent weeks as multiple federal corruption investigations entangle his administration.

A spokesman for the U.S. Attorney's office in Manhattan, which brought the charges, declined to comment. Adams' lawyers did not immediately respond to a request for comment except to send a transcript of his video statement.

One of his lawyers has said that the mayor was cooperating with an investigation but did not say what it was about.

Adams said the charges "would not be surprising" based on the "leaks and rumors" that he said were aimed at undermining his credibility.

If he were forced out of office, Public Advocate Jumaane Williams would become mayor of the United States' largest city with a population of about 8.3 million.

The case is likely to complicate any Adams bid for re-election in 2025. Other Democratic politicians, including New York City comptroller Brad Lander, plan to challenge Adams - once a key ally of Democratic President Joe Biden - for the party's nomination.

"The most appropriate path forward is for him to step down so that New York City can get the full focus its leadership demands," Lander said on X, joining a growing list of politicians to call for his resignation.

Before the news broke, U.S. Representative Alexandria Ocasio-Cortez, also a Democrat, became the first member of congress to urge him to step down, saying it would be "for the good of the city."

Shortly before the announcement, Adams appeared at a reception in New York at the Metropolitan Museum of Art attended by President Joe Biden and Jill Biden, both of whom made remarks. Adams did not address the gathering.

The Times, citing a search warrant, reported in early November 2023 that federal authorities were investigating the possible acceptance by Adams' 2021 campaign of illegal donations, including by the Turkish government.

The probe, conducted by the U.S. Attorney's office in Manhattan, focused on whether Adams' 2021 mayoral campaign conspired with a Brooklyn construction company to funnel foreign money into the campaign through a straw-donor scheme, the Times said.

Authorities have also sought information about Adams' interactions with Israel, China, Qatar, South Korea and Uzbekistan, according to the Times.

Adams, 64, a former police officer who rose to the rank of captain, has repeatedly denied wrongdoing and said he is cooperating with the probe. His lawyers said in a statement on Aug. 15 they had conducted their own investigation into the matters prosecutors were probing and had not found evidence of illegal conduct by Adams.

"To the contrary, we have identified extensive evidence undermining the reported theories of federal prosecution as to the Mayor, which we have voluntarily shared with the U.S. Attorney," said the lawyers, Brendan McGuire and Boyd Johnson.

New York has been in a state of political upheaval for the past month. Police Commissioner Edward Caban resigned on Sept. 12, a week after FBI agents seized his phone. Days later, Adams' chief legal adviser resigned, saying she could "no longer effectively serve" in the position.

On Wednesday, the city's public schools chancellor David Banks said he would retire at the end of the year, weeks after the Times reported his phones were seized by federal agents.