The death, which was first reported in Turkish media, was confirmed by Turkey's Foreign Minister Hakan Fidan at a press conference, according to AFP.
Gülen, who was said to have had health problems for a long time, is reported to have died from an unspecified heart and cardiovascular disease, according to government-friendly Daily Sabah.
Predikant Fethullah Gülen was previously Erdogan's ally and helped his AK party to victory in three elections, but was later accused of trying to overthrow the president and build "a state within a state".
The president claims that Gülen – who had been living in the USA since 1999 – was behind the attempt to carry out a coup in Turkey in 2016. Turkey demanded his extradition, which the USA refused. In 2017, he was stripped of his Turkish citizenship, according to AFP.
Gülen denied the accusations throughout, but Turkey has cracked down hard on anyone who can be linked to him. The so-called Gülen movement has been classified as a terrorist organization by Turkey, and hundreds of thousands of people accused of being affiliated with the movement have been imprisoned or fired from their jobs.
Over 250 people were killed during the coup attempt in 2016, and many more were injured. Many were civilians who got caught in the crossfire between the rebels and loyal security forces. Exactly how the coup was planned and who was behind it is still unclear.
