ANKARA, Turkey (AP) - U.S. Vice President Joe Biden called on Turkish authorities to be patient with the U.S. legal system as Turkey seeks the return of a cleric accused of masterminding last month's failed military coup.

Biden, who met with Turkish officials in Ankara on Wednesday, said the U.S. extradition process would take time as he reaffirmed Washington's cooperation in the case of U.S.-based Muslim cleric Fethullah Gulen. Gulen has denied any involvement in the July 15 coup attempt that killed more than 270 people."I understand the intense feeling your government and the people of Turkey have about him," Biden said at news conference after meeting with Turkish Prime Minister Binali Yildirim. "We are cooperating with Turkish authorities."Our legal experts are working right now with their Turkish counterparts on the production of and the evaluation of material and evidence that needs to be supplied to an American court to meet the requirements under our law in the extradition treaty to extradite Gulen."Biden sought to assuage concerns that the U.S. was shielding Gulen."We have no, no, no, no interest whatsoever in protecting anyone who has done harm to an ally. None," he said. "But we need to meet the legal standard requirement under our law."He also warned that President Barack Obama wouldn't intervene in the extradition process."We should make clear under American law that no president of the United States has authority to extradite anyone under his own power, that only an American court can do that."Were a president to attempt to do that, it would be an impeachable offense," he said.Turkish officials, including President Recep Tayyip Erdogan, have repeatedly called on the U.S. to swiftly extradite Gulen, who lives in Pennsylvania in self-imposed exile.