Earlier Friday it was reported that investigators are also looking into a proposed scheme where Flynn and his son could have received $15 million for delivering an exiled cleric into Turkish hands.
Investigators in Robert Mueller's Russian Federation probe are questioning witnesses about a September 2016 meeting that was alleged to have happened between Michael Flynn, who would later become President Donald Trump's national security adviser, and Rep. Dana Rohrabacher, R-Calif., who has pushed for better relations with Russian Federation.
Erdogan has accused Gulen of orchestrating an attempted coup against his government in 2016.
Federal Bureau of Investigation agents have asked at least four people about a meeting in mid-December at the 21 Club in Manhattan, where Flynn and Turkish government officials discussed removing Gulen, according to the report.
The FBI is seeking to determine if former National Security Adviser Michael Flynn met with senior Turkish officials ahead of President Trump's inauguration to discuss Flynn secretly carrying out directives from Ankara while in the White House, according to reports.
Michael Flynn talks to media as he arrives with is son (l.) at Trump Tower on November 17, 2016.
Former CIA Director James Woolsey, an unpaid adviser to Flynn Intel Group who attended the meeting, has said that the idea of kidnapping Gulen and removing him to Turkey was discussed.
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Because the alleged incident occurred past year it is still within the statute of limitations in the state of California. Crews tweeted that he contemplated fighting the man, but "thought twice about how the whole thing would appear".
Both US media outlets also reported that Mr Flynn and the meeting participants discussed a way to free Turkish-Iranian gold trader Reza Zarrab, who is in a US jail over charges that he evaded US sanctions on Iran.
President Recep Tayyip Erdogan has long sought for the U.S.to extradite Gulen, who resides in the United States.
The report in the Wall Street Journal is the latest of a string of allegations facing Flynn, a retired general and former head of the Defence Intelligence Agency (DIA).
The December meeting also occurred after Flynn and his lawyers had been contacted by the Justice Department for failing to register as a foreign agent.
Lt. Gen. Michael Flynn (ret.), national security adviser, designate speaks during a conference on the transition of the presidency from Barack Obama to Donald Trump at the U.S. Institute Of Peace on January 10, 2017 in Washington.
Participation in an effort to snatch Gulen in the USA could expose Flynn to an assortment of federal charges. Flynn then retroactively registered as a foreign agent.
On November 8, Flynn published an op-ed piece in The Hill that called Gulen "a shady Islamic mullah" and a "radical Islamist".