The Obama administration would entertain an extradition request for the U.S.-based cleric that Turkey's president is blaming for a failed coup attempt, U.S. Secretary of State John Kerry said Saturday.

But he said Turkey's government would have to prove Fethullah Gulen's wrongdoing.

Visiting Luxembourg, Kerry said Turkey hasn't yet requested that the United States send home Gulen, who left Turkey in 1999.

Gulen has harshly condemned the attempted coup attempt by military officers that resulted in a night of explosions, air battles and gunfire that left dozens dead. But Turkish President Recep Tayyip Erdogan's government is blaming the chaos on the cleric, who lives in exile in Pennsylvania and promotes a philosophy that blends a mystical form of Islam with staunch advocacy of democracy, education, science and interfaith dialogue.

Erdogan has long accused Gulen, a former ally, of trying to overthrow the government. Washington has never found any evidence particularly compelling previously.

"We haven't received any request with respect to Mr. Gulen," Kerry told reporters. "We fully anticipate that there will be questions raised about Mr. Gulen. And obviously we would invite the government of Turkey, as we always do, to present us with any legitimate evidence that withstands scrutiny. And the United States will accept that and look at it and make judgments about it appropriately."

"I'm confident there will be some discussion about that," Kerry added.

President Barack Obama on Friday urged all sides in Turkey to support the democratically elected government in Turkey, a key NATO ally.

In a statement issued after a meeting with his national security advisers Obama also urged those in Turkey to show restraint and avoid violence or bloodshed. Obama was to be briefed on the situation Saturday by his national security and foreign policy advisers.

Gulen is understood to maintain significant support among some members of the military and mid-level bureaucrats. His movement called Hizmet includes think tanks, schools and various media enterprises. Gulen and Erdogan only became estranged in recent years.

In a statement, Gulen said he condemned, "in the strongest terms, the attempted military coup in Turkey."

"Government should be won through a process of free and fair elections, not force," he said. "I pray to God for Turkey, for Turkish citizens, and for all those currently in Turkey that this situation is resolved peacefully and quickly."

Gulen sharply rejected any responsibility: "As someone who suffered under multiple military coups during the past five decades, it is especially insulting to be accused of having any link to such an attempt. I categorically deny such accusations."

Reiterating American support for Erdogan's government, Kerry said the U.S. opposed any attempt to overthrow a democratically elected leader. He said a change of government should only come through a legal, constitutional process.

Kerry also said that U.S. military cooperation with its NATO ally has been unaffected by the turmoil. Turkey plays a key role in U.S.-led efforts against the Islamic State in Syria and Iraq.

"All of that continues as before," Kerry said.

He said the U.S. had no prior indication of the coup attempt, which came as Erdogan was on vacation.

It appears not to have been backed by the most senior ranks of the military, and Turkey's main opposition parties quickly condemned the attempted overthrow of the government. Prime Minister Benali Yildirim said 161 people were killed and 1,440 wounded in the overnight violence. He said 2,839 plotters were detained.

"If you're planning a coup you don't exactly advertise to your partners in NATO," Kerry said. "So it surprised everyone. It does not appear to be a very brilliantly planned or executed event."

Turkey plays a key role in U.S.-led efforts against the Islamic State group in Syria and Iraq.