Fethullah Gulen, the US-based cleric accused by Ankara of orchestrating the coup attempt in Turkey, has a wide following in his native country, where he enjoys support among the police and judiciary.

The reclusive Islamic preacher, who lives in a tiny town in the Pocono Mountains of the US state of Pennsylvania, was immediately accused by Turkish President Recep Tayyip Erdogan of being behind the coup attempt.

Gulen however denied any role, and condemned the coup attempt "in the strongest terms."

"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," Gulen said in a statement late Friday.

"I condemn, in the strongest terms, the attempted military coup in Turkey," read the two-paragraph statement.

"Government should be won through a process of free and fair elections, not force.

"I pray to God for Turkey, for Turkish citizens, and for all those currently in Turkey that this situation is resolved peacefully and quickly," he said.

Gulen, 75, was once a close ally of Erdogan but the two fell out in recent years as Erdogan became suspicious of Gulen's movement, Hizmet, and its powerful presence in Turkish society, including the media, police and judiciary.

The preacher moved to the United States in 1999, before he was charged with treason in his native country.

He has since led a secluded life in Pennsylvania, declining interviews and rarely making public appearances.

- A 'state within a state'?-

The power struggle between the two foes came to a head in late 2013 after judicial officials thought to be close to Gulen brought corruption charges that directly implicated some of Erdogan's inner circle, including his son Bilal.

Erdogan launched a series of counterattacks, purging hundreds of army officers, including top generals, shutting down schools operated by Hizmet and firing hundreds of police officers.

Erdogan has also gone after newspapers believed to be sympathetic to his rival, firing their editors or shutting them down.

Turkish authorities have accused the preacher of seeking to establish "a state within a state" in Turkey, but Hizmet officials insist that Gulen is committed to democratic reform and interfaith dialogue.

"For more than 40 years, Fethullah Gulen and Hizmet participants have advocated for, and demonstrated their commitment to, peace and democracy," the Alliance for Shared Values said in a statement on Friday.

"We have consistently denounced military interventions in domestic politics. These are core values of Hizmet participants. We condemn any military intervention in domestic politics of Turkey."

The group said it did not wish to speculate on the unfolding crisis in Turkey and denounced as "highly irresponsible" comments by Erdogan's supporters concerning Gulen's involvement in the coup attempt.

Hizmet - meaning service in Turkish - advocates a mix of Sufi mysticism and harmony among people based on the teachings of Islam.

However it is not a religious effort: their work centers on community service, education, human rights, democracy, and "intercultural and interfaith dialogue for peaceful coexistence," according to the Alliance for Shared Values website.