NEW YORK >> Federal authorities investigating New York Mayor Eric Adams’ campaign fundraising have been examining valuable flight upgrades they believe he received from Turkish Airlines that elevated him to its highest class of seats available on international trips, according to people with knowledge of the matter.

The scrutiny is part of a broad corruption inquiry that already has led the FBI to search the homes of the former top New York-based executive of Turkish Airlines and aides to Adams.

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

The broader investigation has focused at least in part on whether the Turkish government conspired with Adams’ mayoral campaign to funnel foreign money into its coffers and whether Adams pressured the New York City Fire Department to sign off on Turkey’s new high-rise consulate in Manhattan despite safety concerns.

Federal prosecutors in Manhattan and FBI agents conducting the inquiry have developed evidence that Öcal helped arrange at least some of the upgrades in coordination with Abbasova, two of the people familiar with the federal investigation said. They and others interviewed for this article spoke on condition of anonymity to discuss the ongoing federal investigation.