Former national security adviser Michael Flynn and his son met with members of the Turkish government last December to discuss a plan to kidnap a political enemy of Turkey’s president in exchange for millions of dollars, according to two new reports.

Special Counsel Robert Mueller is investigating the plot, which Flynn reportedly discussed with the Turkish delegation during a meeting in mid-December at the 21 Club in New York City.

Flynn, a retired lieutenant general, had by that point had been tapped as then-President-Election Trump’s national security adviser.

According to The Journal, Flynn and his son, Michael Flynn Jr., were to be paid as much as $15 million to forcibly remove Muslim cleric Fethullah Gulen from the U.S. The idea of transporting Gulen via private jet to a Turkish prison was discussed, The Journal’s sources told the newspaper.

Gulen, who has lived in exile in Pennsylvania since 1999, is a bitter enemy of Turkish president Recep Tayyip Erdogan. Though former allies, Erdogan has pressed the U.S. to extradite Gulen, who is in his 70s. Erdogan has accused Gulen of masterminding last July’s failed coup attempt and of attempting to undermine Turkish society and government.

NBC News had a follow-up report to The Journal story which includes a few additional details. According to the network, the Mueller investigation is looking into whether Flynn was to be “paid to carry out directives from Ankara secretly while in the White House” with payments to be made either “directly or indirectly.” (RELATED: As Foreign Agent For Turkey, Flynn Formed ‘Investigative Laboratory’ To Make ‘Criminal Referrals’ Against Turkish Cleric)

The investigation is also looking into whether the idea of freeing Turkish-Iranian gold trader Reza Zarrab was discussed at the meeting. Zarrab is scheduled to go to trial later this month over a scheme to skirt U.S. sanctions against Iran. Erdogan has also pleaded with the U.S. government to drop the case against Zarrab. It is widely believed that Zarrab has damaging information about Erdogan and his family.

Mueller, a former FBI director, was initially tasked with investigating Russian interference in the presidential campaign. But the probe has expanded quickly to include business activities of Flynn and former Trump campaign chairman Paul Manafort that appear unrelated to Russia. Mueller indicted Manafort earlier this month for money laundering.

Flynn’s meeting in December followed one that he attended on Sept. 19, 2016 with two top Turkish government officials, Turkish foreign affairs minister Mevlut Cavusoglu and energy minister Berat Albayrak.

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. Flynn has denied the allegation. (RELATED: Flynn Reportedly Discussed Covert Kidnapping Plan With Turkish Government)

Flynn disclosed that meeting, but not the one in December, when he registered as a foreign agent of Turkey in March, just weeks after he was fired from the White House. The administration says that Flynn was let go for lying to Vice President Mike Pence about his interactions with Russian ambassador Sergey Kislyak.

It is unclear if the White House was aware of Flynn’s discussion with Turkish government officials.

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. The Daily Caller has reported that Flynn was contacted by DOJ’s National Security Division on Nov. 30. (RELATED: Here’s What Prompted Michael Flynn To Register As A Foreign Agent Of Turkey)

He registered as a foreign agent on March 7.

Flynn’s ties to Turkey were first reported on Nov. 11, in a Daily Caller report revealing that Flynn’s consulting firm, Flynn Intel Group, had signed a lobbying contract with a Turkish businessman connected to Erdogan. Flynn had written an op-ed in The Hill on Election Day calling on the U.S. government to extradite Gulen. The former Defense Intelligence Agency director had not publicly discussed the topic up to that point. (RELATED: Michael Flynn Is Lobbying For Obscure Dutch Company With Ties To Turkish Government)

An investigation of Flynn Intel Group’s lobbying activities revealed that the firm had recently started lobbying for a Netherlands-based company called Inovo BV. That company turned out to be a one-man shell company owned by Ekim Alptekin, the chairman of the Turkish-U.S. Business Council, which is controlled by the Turkish government.

Alptekin has denied any wrongdoing, but he has given inconsistent answers about his work with Flynn. Alptekin reportedly met with Mueller’s investigators during a trip he made to the U.S. in May.

When Flynn registered as a foreign agent, he revealed that Flynn Intel signed a $600,000 contract with Inovo BV in Aug. 2016. Inovo eventually paid Flynn Intel a total of $530,000 for three months worth of work. Curiously, Flynn Intel made two separate $40,000 payments back to Inovo BV in the middle of its contract.

Mueller’s team is reportedly investigating whether kickbacks were involved in the Flynn-Inovo deal.

FLYNN SAYS NO LINES CROSSED WITH RUSSIA, CONCERNED ABOUT CONSTANT LEAKS AFTER RESIGNATION

Follow Chuck on Twitter