Turkey arrested three people Monday, including the local official for Reporters Without Borders and the head of a key human rights organization, over support for an embattled newspaper that targets a Kurdish audience.
They are accused of helping to spread "terrorist" propaganda, the Dogan news agency reported.
Ozcan Kilic, a lawyer handling the case, told dpa that prosecutors issued arrest warrants for Erol Onderoglu, from the journalist advocacy group, the chairman of the Turkish Human Rights Foundation Sebnem Korur Fincani, and journalist Ahmet Aziz Nesin.
Ozgur Gundem, a pro-Kurdish newspaper, has been under pressure from the government over alleged ties to the banned Kurdistan Workers' Party (PKK). The three stepped in as symbolic editors for a day in support.
More than 40 prominent journalists and public figures joined the campaign this year to support the paper, with investigations opened against many, the Dogan report said.
Turkey and Kurdish militants restarted armed conflict last year, after a ceasefire and peace talks collapsed. Turkey is ranked 151 out of 180 countries on the Press Freedom Index compiled by Reporters Without Borders.
Condition for journalists in Turkey have worsened over the past year, activists say.
"The Turkish authorities use the anti-terror laws as a tool to silence opposition, especially the ones who are speaking out on the Kurdish issue,” said Andrew Gardner of Amnesty International.
The European Union is demanding Turkey change its vague anti-terror laws so that Turkish citizens can be granted visa-free access to the bloc, but Ankara is refusing.
This is part of the wider deal between Turkey and Europe on the migration issue, with Ankara expected to help stem flows of refugees and economic migrants.