New York City Mayor Eric Adams is facing federal criminal charges, according to CBS News, the BBC's US partner.

Federal investigators searched Gracie Mansion, the mayor's official residence, on Thursday morning, hours before prosecutors were expected to reveal details of the indictment.

Adams, 64, was elected to lead the most populous US city nearly three years ago on a promise to rein in crime.

But he and a string of top officials in his orbit have faced growing scrutiny as part of multiple federal corruption probes, including whether his campaign received illegal foreign donations from Turkey.

The exact charges will not be known until the indictment is unsealed.

Adams would become the first mayor in New York City's history to be charged while in office.

He released a video statement late on Wednesday where he vowed to fight the charges and remain in office, asking New York residents for both "prayers and patience".

"I will fight these injustices with every ounce of my strength and my spirit," he says in the video, adding "I am innocent" and he plans to request an "immediate trial so New Yorkers can hear the truth".

He also took on the flurry of calls for him to resign.

"Now, if I am charged many may say I should resign because I cannot manage the city while fighting the case.

"I can also understand how everyday New Yorkers would be concerned that I cannot do my job while I face accusations, but I have been facing these lies for months."

Federal prosecutors are expected to unseal the indictment on Thursday, when Adams will make an initial court appearance, CBS News reports.

The reported charges come less than a year after federal agents seized Adams' electronic devices and searched the home of Brianna Suggs, his chief fundraiser.

It was later revealed that the US attorney's office in Manhattan was looking into whether Adams' 2021 mayoral campaign team conspired with the government of Turkey to funnel illegal donations into the campaign.

The New York Times reported on Monday that prosecutors subpoenaed the campaign and the mayor's office for information related to five other countries: Israel, China, Qatar, South Korea and Uzbekistan.

Adams has remained steadfast that he would remain in office even as a growing list of officials have called for his resignation. Earlier Wednesday, US Representative Alexandria Ocasio-Cortez - a popular figure in left-leaning New York - joined that list.

"I do not see how Mayor Adams can continue governing New York City," Ocasio-Cortez wrote on X. "For the good of the city, he should resign."

Ocasio-Cortez referenced a recent "flood of resignations and vacancies" that she said were threatening city government's ability to function.

Adams's reported indictment comes weeks after federal agents seized electronic devices belonging to three people closely affiliated with him - schools chancellor David Banks, his brother Deputy Mayor Phil Banks, and his fiancée Deputy Mayor Sheena Wright.

In a surprise announcement on Tuesday, David Banks announced he would be stepping down from his role at the end of the year.

The US attorney’s office in Manhattan is investigating another Banks brother, Terence, over a possible bribery scheme involving his consulting firm and city contracts.

Prosecutors in that office are also looking into bribery claims against the twin brother of former New York Police Commissioner Edward Caban, who resigned earlier this month weeks after his phone was seized by federal agents.

Acting Police Commissioner Thomas Donlon had his own homes searched last Friday.

In the past two weeks, the mayor’s chief legal counsel and the city health commissioner have also stepped down.

Adams, who is only the second black person to run New York City, is facing a growing list of Democratic challengers ahead of his re-election bid next year.

New York’s Democratic Governor Kathy Hochul, a close ally who has yet to comment on the indictment, has the power to remove Adams from office.

If Adams’ tenure ends prematurely, Jumaane Williams, the city’s public advocate, is next in line to become the city’s acting mayor.