Pro Erdogan supporters wave a Turkish national flag during a rally at Bosporus Bridge in Istanbul, one of the key battlegrounds in Friday night's coup attempt. (Umit Turhan Coskun/AFP/Getty Images)

Turkey’s top diplomat urged the United States on Friday to quickly hand over a self-exiled cleric whom Turkish leaders have linked to last week’s coup attempt — an issue that risks causing serious tension between the two allies.

Foreign Minister Mevlut Cavusoglu told the state-run broadcaster TRT that Turkey was ready to take part in a commission proposed by Washington to discuss the extradition of Fethullah Gulen. But Cavusoglu insisted there was no need for it to take a long time.

“If you want to draw out the Gulen extradition issue, it can take years, but if you are decisive, it can be completed in a short period,” he said, according to the Reuters news agency.

Since a failed July 15 coup by military units, Turkey has carried out a widespread crackdown on members of the army, police, judiciary and educational institutions. Tens of thousands of people have been arrested, fired or suspended on suspicion of sympathies to Gulen.

[The cleric blamed by Turkey leads a global movement from the Poconos]

The government maintains that followers of Gulen, who lives in Pennsylvania, were behind the attempted overthrow, and it has demanded that he be returned to Turkey. But the United States has insisted on clear evidence of the cleric’s involvement.

Any blows to U.S.-Turkish relations could spill over to other crises around the region.

Turkey, a member of NATO, is a critical front-line partner in the fight against the Islamic State and efforts to control the flow of migrants into Europe. There also is concern that Turkish society and freedoms could come under much tighter control amid the purges and probes following the unsuccessful coup.

Gulen has denied any link to the plot, implying instead that President Recep Tayyip Erdogan staged it as part of a bid to consolidate power.

In a possible sign of rising friction over Gulen’s extradition, Turkey’s ambassador to the United States would offer only a brief response when asked by reporters whether he thought the United States had played a role in the attempted coup.

“I hope not,” Serdar Kilic said during a news conference at the Turkish Embassy in Washington.

He did not provide details regarding Turkey’s extradition request for the dissident cleric beyond saying that the “necessary documentation” had been submitted and that discussions with U.S. authorities are ongoing.

Fethullah Gulen is an Islamic scholar and cleric from Turkey. He left Turkey in 1999, and is now living in self-imposed exile in Pennsylvania. (Claritza Jimenez,Jason Aldag/The Washington Post)

Erdogan, meanwhile, called on Turks to continue nightly protests a week after the coup attempt, calling them an “antidote” to the mutiny. And he has declared July 15 “Martyr Remembrance Day” to honor those who lost their lives resisting the military power grab.

“I am requesting my heroic nation, which thwarted the armed coup attempt with its foresight and courage, to continue the democracy watch on the streets until our country gets out of this difficult situation for good,” Erdogan said late Thursday.

The president added that more than 10,000 people have been detained so far.

Among them is one of Turkey’s most prominent human rights defenders, Orhan Kemal Cengiz, who was stopped at Istanbul’s Ataturk Airport and taken to a local police station.

Tens of thousands of others have been put under investigation.

Dan Lamothe and Ishaan Tharoor in Washington contributed to this report.

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Today’s coverage from Post correspondents around the world