Turkish media report that close associates of self-exiled Imam Fethullah Gülen were arrested by the authorities while attempting to seek asylum in Greece.
Mehmet Güdem and his wife Mine, who together with 18 other people tried to cross into Greek territory through the Evros River, were stopped by the Turkish Gendarmerie and detained.
Of the 20 people, it was found - according to the Turkish Authorities - that 16 were members of Gülen's so-called FETÖ, and the rest were members of Kurdish organisations, which Turkey characterises as "terrorist".
Turkish newspaper reports state that Mehmet Güdem, a journalist and former member of the Journalists and Writers Foundation, is the author of the book "11 Days with Fethullah Gülen".
The book was published in 2005 when Erdoğan-Gülen relations were at their best and was serialised in the Milliyet newspaper.
Güdem was sentenced to 6.5 years in prison for membership in an armed terrorist organisation.
He was initially arrested in 2017, as part of an investigation by the General Prosecutor's Office of Istanbul against the directors, members and employees of the Journalists and Writers Foundation.
The author has written the biographies of many Turkish politicians, including former Turkish President Abdullah Gül .