An Istanbul court on Saturday remanded the board chairman of opposition Turkish newspaper Cumhuriyet in custody, a day after he was detained, state-run news agency Anadolu said.
Akin Atalay was apprehended at Istanbul's main international airport Friday, the latest move in an intensifying crackdown on the daily that has alarmed Turkey's European allies.
Nine of the newspaper's staff were arrested last week including its editor in chief, as concern swells at home and abroad over media freedom in Turkey in the wake of July's failed military coup.
The staff are accused of "terrorist" activities in connection with the outlawed rebels of the Kurdistan Workers Party (PKK) and the US-based preacher Fethullah Gulen, arch-foe of President Recep Tayyip Erdogan, who authorities accuse of masterminding the coup.
The paper has in recent years taken a strong line against Erdogan's ruling Islamic-rooted Justice and Development Party (AKP) and has embarrassed his government with multiple damaging scoops.
Turkish authorities have unleashed a vast purge since the July 14 coup, with around 35,000 people arrested and tens of thousands more losing their jobs -- including military officers, judges, teachers, civil servants and journalists -- accused of links to the plotters.
Since the coup attempt, more than 100 journalists have been arrested while 170 media outlets including newspapers and broadcasters have been closed down, according to the Turkey Journalists' Association.
Turkey was ranked 151st of 180 countries in the 2016 World Press Freedom index published by the campaign group Reporters Without Borders (RSF).