ISTANBUL (AP) — Turkey's official news agency says a court has reissued detention warrants for four human rights activists who were released earlier this week.

Anadolu news agency said the court on Friday accepted an objection filed by the Istanbul prosecutor's office to the activists' release. The four activists were initially released Tuesday after surrendering their passports and they were required to regularly present themselves at a police station.

The activists are part of a group detained earlier this month on an Istanbul island during a digital security training course.

Six other people, including Amnesty International's country director Idil Eser and German citizen Peter Steudtner, were arrested Tuesday pending trial on the charge of aiding terror groups. Germany has called on Turkey to immediately release Steudtner, who is a human rights trainer.