Fethullah Gulen, a former ally of Erdogan turned chief foe, was not present at the start of the proceedings in Istanbul, with Washington failing to grant Turkish requests for his extradition from his secluded compound in Pennsylvania.

A U.S.-based Turkish preacher who has emerged as an arch-enemy of President Recep Tayyip Erdogan went on trial in absentia Wednesday along with several former police chiefs charged over the corruption allegations that hit the Turkish leader in 2013.

Fethullah Gulen, a former ally of Erdogan turned chief foe, was not present at the start of the proceedings in Istanbul, with Washington failing to grant Turkish requests for his extradition from his secluded compound in Pennsylvania.

He is being tried along with dozens of former police officers, including the former head of Istanbul police Yakup Saygili and the city’s ex-deputy criminal police chief Kazim Aksoy, both of whom are said to have ordered the graft probe.

The pair have been held in detention since September 2014 and were both in court at the start of the trial.

At total of 69 people including Gulen are on trial, facing terms ranging from seven years to 330 years.

The judge at Istanbul’s main courthouse opened the proceedings by conducting a roll call of those present, an AFP correspondent said.

The corruption allegations directly implicated some of Erdogan’s inner circle, including his son Bilal. The government denied the claims, which it said came from Gulen and his acolytes in the judiciary and police.

Erdogan, his son Bilal, son-in-law Berat Albayrak and Turkey’s spy chief Hakan Fidan are among the plaintiffs in the case, along with four former ministers who lost their jobs over the corruption allegations.

The top suspects are charged with plotting to topple the Turkish government with the graft allegations, as well as membership of a “terrorist group.”

The scandal was seen as one of the biggest challenges to the dominance of then Prime Minister Erdogan. He survived the allegations, however, and went on to become president in August 2014.

Despite living outside of Turkey, Gulen built up huge influence in the country through allies in the police and judiciary, media and a vast network of cramming schools designed to make up for deficiencies in the state education system.

Ankara now accuses Gulen of running what it calls the Fethullahaci Terror Organisation/Parallel State Structure (FeTO/PDY) and seeking to overthrow the legitimate Turkish authorities.

Gulen supporters decry the accusations as ridiculous, saying all he leads is a more informal group known as Hizmet (Service).

Related articles across the web

• Turkey: Everyone Needs A Way Out
• Erdogan Vows to 'Cleanse' Turkey of PKK as Attacks Kill 25
• Erdogan calls MP 'traitor' for telling RT that ISIS got chemical weapons via Turkey
• Number of people forced to flee war, violence to hit record in 2015: UN
• Erdogan hints at détente
• Turkey: Everyone Needs A Way Out
• Five Events that Explain Current Russian-Turkish Tensions
• Is The Turkish Government Shifting Its Shooting Down Of A Russian Su-24 Blame To Its Air Force Chief?
• Russia Destroys 1,200 ISIS Oil Trucks From Turke
• Putin: Turkish downing of Russian plane was an 'enemy act'