Turkey arrested several people Monday, including the local official for Reporters Without Borders and the head of a key human rights organization, over their 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; Sebnem Korur Fincani, the chairman of the Turkish Human Rights Foundation; 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.
The UN Correspondents Association said late Monday that another journalist, Razi Canikligil of the English-language daily newspaper Hurriyet, also has been arrested in Istanbul by Turkish police.
Giampaolo Pioli, the president of the association, said in an email that Canikligil was arrested based on articles he wrote regarding Turkish authorities.
The association considers the arrest "a grave violation of freedom of the press" and asked that UN Secretary General Ban Ki-moon intervene, Pioli said in an email.
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.