Police in Istanbul have detained a prominent investigative journalist, Ahmet Sik, in connection with his social media postings.
The arrest of Sik, who has been jailed previously, came shortly before writer Asli Erdogan and linguist Necmiye Alpay appeared in a Turkish court.
Many writers and journalists have been arrested in Turkey since the July coup attempt, in which military rebels tried to oust President Recep Tayyip Erdogan.
Sik confirmed his arrest in a tweet.
"I am being detained. I will be taken to the prosecutor's office regarding a tweet," he tweeted.
Sik has been accused of spreading "terrorist propaganda", reports say.
Kurdish links
Asli Erdogan, 49, and Necmiye Alpay, 70, are among nine suspects charged over their links to the pro-Kurdish newspaper Ozgur Gundem, which was shut down in August.
The authorities regard Ozgur Gundem as a mouthpiece for the banned Kurdistan Workers' Party (PKK), an armed group fighting for more Kurdish autonomy. Turkey and its Western allies regard the PKK as a terrorist organisation.
Free speech campaigners Pen say the Turkish authorities have detained almost 150 writers and journalists since the abortive July coup.
Sik and journalist Nedim Sener were previously jailed in 2011-2012. The authorities banned Sik's book The Imam's Army, which examined the life and work of Fethullah Gulen, the US-based cleric blamed by the Turkish government for the July coup attempt.
A version of the book was however published in November 2011.