New York City Mayor Eric Adams is facing another legal matter that could cast even more of a negative light on his administration. Federal investigators are looking into complimentary flight upgrades he received from Turkish Airlines.

The investigation aims to ascertain whether corruption was involved in Adams’ relationship with the airline and other elements in Turkey.

The scrutiny is part of a broad corruption inquiry that has already led the F.B.I. to search the homes of the former top New York-based executive of Turkish Airlines and aides to Mr. Adams, who has frequently traveled abroad and has made no secret of his affinity for flying on the Turkish carrier.

The investigation burst into public view in November after F.B.I. agents searched the homes of the former airline executive, Cenk Öcal, the mayor’s liaison to the Turkish community, Rana Abbasova, and his chief fund-raiser, Brianna Suggs — and seized Mr. Adams’s electronic devices.

The inquiry has shaken an administration that has become increasingly mired in investigations and beset by legal and ethical problems.

This move is part of a broader investigation into the relationship between Adams, his aides, and a top Turkish Airlines executive.

Sources have said at least part of the investigation involves whether donations from Turkey were traded for political favors, including possible pressure exerted on the New York Fire Department after a delay with the operating certificate of the new Turkish consulate.

Mayor Adams has maintained his innocence. Brendan McGuire, the mayor’s attorney, explained that “As borough president, the mayor consistently disclosed his official travel to Turkey, did not receive any improper upgrades and did nothing inappropriate in exchange for an upgrade.”

In November, it was revealed that the FBI seized Adams’ electronic devices while executing a search warrant at his home. At the time, the mayor insisted he had done nothing wrong.

Adams spoke with a news outlet Thursday, and although he didn’t discuss the specifics of the case, he said he was “extremely comfortable” with his campaign’s conduct:

I feel extremely comfortable about how I comply with rules and procedures.

I hold myself to a high standard, and I hold my campaign to a high standard, and I hold my staff at City Hall to a high standard.

I’m very clear that it is my responsibility to hold myself to a high standard and I will comply with any inquiry that is made and I am demanding that my team do the same.

The FBI’s investigation comes as Adams is facing other legal matters. He was recently accused of sexually assaulting a former police officer. She alleges that Adams asked for sexual favors in exchange for helping her progress in her career. The mayor claims the assault “never happened” and said he does not “even know who the person is.”

As the city grapples with a constant influx of illegal immigrants and asylum seekers, Adams has been the subject of scrutiny as the city’s budget is stretched thin from having to take in so many people. This investigation only adds more to his troubles.