A new trial has opened in Turkey against a U.S.-based Muslim cleric who is President Recep Tayyip Erdogan's chief foe, over accusations that his influential movement engaged in espionage and tried to topple the government.

Fethullah Gulen, who lives in self-imposed exile in Pennsylvania, went on trial in absentia on Monday and faces life imprisonment if found guilty. More than 120 other people, including former police officials, are also on trial.

Gulen is already being prosecuted for allegedly plotting against the state by masterminding corruption probes in 2013 that targeted people close to the Turkish leader.

The latest trial stems from accusations that Gulen-affiliated police officers conspired against an Islamic group and used the group as justification to conduct illegal wiretaps.

The government has designated Gulen's movement a "terror organization."