Turkey has dismissed as "utterly false, ludicrous and groundless" a report that Turkish officials may have discussed paying millions of dollars to have a U.S.-based Muslim cleric kidnapped.

The Wall Street Journal reported Friday that Special Counsel Robert Mueller was investigating an alleged plot involving former U.S. National Security Adviser Michael Flynn and his son to hand Fethullah Gulen over to Ankara for as much as $15 million.

Turkey blames the cleric and his supporters for a July 2016 military coup attempt that killed 250 people. Gulen, who lives in Pennsylvania, has denied being behind it.

The Turkish Embassy in Washington reiterated demands late Saturday for the United States to extradite Gulen so he can stand trial. The embassy in a statement rejected "all allegations that Turkey would resort to means external to the rule of law" to get Gulen back on Turkish soil.

Flynn's lawyers also have disputed the Journal report saying Mueller was looking into a meeting where Flynn allegedly discussed a plan that would pay him and his son "to forcibly remove" Gulen.

Flynn, a retired lieutenant general, did lobbying work for Turkey last year.

"Out of respect for the process of the various investigations regarding the 2016 campaign, we have intentionally avoided responding to every rumor or allegation," the lawyers said in a statement.

"But today's news cycle has brought allegations about General Flynn, ranging from kidnapping to bribery, that are so outrageous and prejudicial that we are making an exception to our usual rule: they are false," they said. .

Michael Flynn Jr.'s attorney declined to comment on the allegations.

Gulen has been living in the U.S. for nearly two decades. He is a former ally of Turkish President Recep Tayyip Erdogan until their 2013 public falling-out led the government to declare Gulen's network a terror group.

Nearly 50,000 people are behind bars in Turkey and more than 100,000 civil servants have been dismissed from their jobs for alleged links to the cleric's network in the government's crackdown after the failed coup.

Also behind bars in Turkey for alleged links to Gulen is U.S. pastor Andrew Brunson, who has lived in Turkey for over 20 years. Erdogan said in September the U.S. was pressing Turkey to return a "cleric" while refusing to hand over another "cleric."

The Turkish Embassy said the Turkish people find Gulen's continued refuge in the U.S. "perplexing and deeply frustrating."

Complicating relations further is the case of a Turkish-Iranian businessman on trial in the U.S. for evading U.S. sanctions on Iran. A former Turkish economy minister and an executive of a state-owned Turkish bank have also been indicted.

In a meeting last week, Turkish Prime Minister Binali Yildirim and U.S. Vice President Michael Pence discussed the cases among other sources of strain, including the U.S. backing of Syrian Kurdish militants in the war against the Islamic State group.

Turkey has been infuriated by the U.S. support for a group it considers an extension of the outlawed Kurdistan Workers' Party or PKK, which has waged an insurgency within Turkey for more than 30 years.