The United States held firm Wednesday in rebuffing Turkey's demand that it immediately extradite Muslim cleric Fethullah Gulen whom Ankara blames for last month's failed military coup, saying it has yet to receive any evidence linking him to the putsch.
U.S. Vice President Joe Biden said the White House is determined to listen to "every scrap of evidence" Turkey provides before deciding if it will extradite the Muslim cleric.
Gulen lives in the eastern state of Pennsylvania, and Turkey is demanding his immediate extradition, accusing him of organizing last month's failed military coup -- a charge he denies.
Biden met in Ankara Wednesday with Turkish President Recep Tayyip Erdogan. He tried to head off Erdogan's impatience by explaining that American courts require firm evidence before a suspect is surrendered to another country.
WATCH: Biden assures Turkey of staunch US support
"You can't go into the court and say, 'This is a bad guy' ... you have to say, 'This is a guy or woman who committed the following explicit crime,'" Biden said.
He said prosecutors need to show a judge probable cause, and that sometimes courts move slowly. Biden noted that U.S. President Barack Obama could be impeached if he orders a foreign national extradited without a proper hearing.
During his one-day visit to Ankara, Biden told a news conference that the United States has "no interest in protecting anyone who has done harm to an ally."
He said the U.S. is continuing to cooperate with Turkish officials in analyzing claims about Gulen's purported actions linked to the attempted coup that left 240 people dead.
But in an article published in Turkey's Milliyet newspaper, Biden said that while Turkey has sent Washington information about the 75-year-old Gulen's "alleged activities predating the attempted coup, we have not yet received an extradition request or any evidence from Turkey relating to the attempted coup."
Turkish Prime Minister Binali Yildirim has said any delay in sending Gulen back to Turkey could harm U.S.-Turkish relations.
Biden told the news conference he understood Turkey's anger at the U.S. delay in handling the extradition request, but said a U.S. court must consider whether there are legitimate legal grounds to arrest him and turn him over to Turkish authorities based on the extradition treaty between the two countries.
Turkey has arrested or fired 80,000 government workers, judges, academics and school teachers it believes were sympathetic to Gulen or somehow involved in the coup attempt launched by a group of renegade military officers.
Erdogan, on vacation the night of the coup attempt, says he narrowly escaped being captured before government forces loyal to Ankara repelled dissidents looking to overthrow him.
Biden sought to dispel any notion of U.S. complicity in the uprising, calling those who carried out the attack "cowardly, treasonous."
"We did not have any foreknowledge," he said. "The people of the United States abhor what happened. The people of Turkey have no greater friend than the United States of America."
Yildirim said any disputes with the U.S., a NATO ally, should not be allowed to harm their long-term friendship. But Yildirim said he wants the extradition proceedings to be conducted without delay.
Biden's visit to the Turkish capital came as Ankara's military forces, working in tandem with U.S. jet fighters, launched their first offensive into Syria to target Islamic State militants and Kurdish fighters in the aftermath of last weekend's suicide bombing of Kurdish wedding in a nearby Turkish town that killed at least 54.
Erdogan has blamed Islamic State for the attack.