By Adem Demir

ISTANBUL

The Chief Prosecutor's Office in Istanbul has written a letter to U.S. authorities demanding the detention of Fetullah Terrorist Organization (FETO) leader Fetullah Gulen, judicial sources told Anadolu Agency Saturday.

The Turkish Ministry of Justice will forward to U.S. officials, the sources said.

The letter stated that the coup attempt was carried out with the instructions of U.S.-based preacher Fetullah Gulen, who has been living in self-imposed exile in Pennsylvania since 1999.

The letter also mentioned that Gulen was facing such charges as "attempting to eliminate the government of Republic of Turkey and prevent it from functioning", "attempting to assassinate the president" and "attempting to demolish the Turkish parliament with the aim of preventing it from functioning".

Ankara has repeatedly said the July 15 coup attempt was organized by followers of Gulen and his FETO group.

Turkey has said Gulen is the mastermind behind a failed coup attempt last month that martyred 240 people and injured nearly 2,200 others.

Turkey has since requested Gulen’s extradition from the U.S.

The U.S., however, said it is still reviewing the request's formality.

Gulen is also accused of leading a long-running campaign to overthrow the state through the infiltration of Turkish institutions, particularly the military, police, and judiciary, forming what is commonly known as the parallel state.

*Can Erozden in Ankara contributed to this story.