U.S. President Donald Trump told his Turkish counterpart Tayyip Erdogan that Washington was working on extraditing a U.S.-based Muslim cleric accused of orchestrating a failed Turkish coup in 2016, Turkish Foreign Minister Mevlut Cavusoglu said on Sunday.

"In Argentina, Trump told Erdogan they were working on extraditing Gulen and other people," Cavusoglu said at conference in Doha, referring to the G20 summit in Argentina from Nov. 30 to Dec. 1.

Read more: Syrian Kurds Declare Turkish Threats an 'Act of War' as U.S. Troops Dig in for Long Stay

Whether or not the U.S. can legally extradite Gulen is an open question as the U.S. has long refuted Turkish evidence implicating the cleric in the 2016 coup. NPR's Justice Department correspondent tweeted in response to Cavusoglu's claim, "If this is true, will the State Dept and the Justice Dept follow his lead? Argument from US govt has been for years there is no credible evidence Gulen broke the law...."

Turkey has long sought the extradition of Gulen, who has lived in self-imposed U.S. exile for nearly two decades. A former ally of Erdogan, he is blamed by Turkish authorities for the failed coup when rogue soldiers commandeered tanks and helicopters, attacked parliament and shot unarmed civilians.

Gulen denies any involvement in the failed putsch. Trump said last month he was not considering extraditing the preacher as part of efforts to ease Turkish pressure on Saudi Arabia over the killing of Saudi journalist Jamal Khashoggi in Istanbul.

Erdogan said last week Turkey would start new initiatives abroad to target the financing of Gulen supporters.

"I have recently seen a credible probe by the FBI on how the Gulen organisation avoids taxes," Cavusoglu told a conference in Doha.