Amnesty International says Turkish police have detained the group’s director in Turkey along with other human rights activists.
The nongovernmental rights group says its Turkey director, Idil Eser, was detained on July 5 along with activists and trainers during a "digital security and information management workshop" near Istanbul.
Turkey’s Hurriyet daily reports that 12 people were arrested during a police raid at a hotel on the Buyukada Island retreat.
There was no immediate comment from Turkish police or any indication of what the rights activists were accused of.
Amnesty International Secretary-General Salil Shetty said the group is “profoundly disturbed and outraged that some of Turkey's leading human rights defenders, including the director of Amnesty International Turkey, should have been detained so blatantly without cause."
Shetty said the activists should be "immediately and unconditionally released."
Their whereabouts were not known.
The detentions come less than a month after Amnesty International's Turkey chair, Taner Kilic, was remanded in custody on what the group described as "baseless charges" of having ties to Fethullah Gulen, the alleged mastermind of Turkey’s failed July 15, 2016, coup.
Meanwhile, the European Parliament has advised the European Union to formally suspend accession talks with Turkey amid growing concerns over human rights and rule of law.
The parliament voted 477-64 with 97 abstentions on July 6 to approve a nonbinding report recommending the suspension of talks following Turkey's referendum in April that approved constitutional amendments to give the president sweeping new powers.
The parliament called on the EU's 28 member states to formally suspend the talks "without delay" if the constitutional reforms are implemented without change by Ankara.
Omer Celik, the Turkish minister in charge of relations with the bloc, said the report was "geared toward sabotaging relations."
Tensions between Turkish President Recep Tayyip Erdogan and the EU have been high because of European concerns that he was trampling on rights and punishing opponents in a clampdown after a failed coup attempt against him in July 2016.