Turkish police took 18 academics into custody and were seeking to detain seven others on Friday over a petition calling for peace with Kurds in the south-east of the country amid an uptick in violence.
The petition - which accuses Turkey's government and security forces of carrying out a "massacre" of the country's Kurdish minority and others - was launched this week as fighting between the armed Kurdistan Workers' Party (PKK) and the state intensified.
Chief Prosecutor Mustafa Kucuk accused the petition signers of spreading terrorist propaganda and "insulting the moral integrity of the state."
Those arrested are from universities in Kocaeli and Bursa provinces, the state-run Anadolu news agency reported.
The petition has drawn the ire of the country's political leaders. President Recep Tayyip Erdogan has been launching daily verbal assaults on the academics, calling the petition "vile and barbaric" on Friday and accusing the signers of treason.
Prime Minister Ahmet Davutoglu from the conservative and Islamic-rooted Justice and Development Party (AKP) implied the academics had chosen to "align" themselves with terrorists.
The petition's 1,100 initial signatories has since doubled, according to organizers. It has received support from abroad, including noted US linguist Noam Chomsky.
Human rights groups have been critical of the strict round-the-clock curfews that Turkish security forces are implementing in civilian neighbourhoods in the south-east. Kurdish officials say dozens of civilians have been killed.
The US Embassy in Ankara said it was concerned by the detentions and, though it does not necessarily support the statement by the academics, is worried about a "chilling effect" on political discourse.
"Expressions of concerns about violence do not equal support for terrorism," Ambassador John Bass said in a statement. "Criticism of the government does not equal treason."
The Council of Europe also voiced concern, saying: "Reports from Turkey about arrests of several academics and intellectuals today are very worrying."
Members of the largest opposition group in the Turkish parliament, the centre-left People's Republican Party (CHP), were also critical of the prosecutors, saying the criminal proceedings against the academics are "unlawful, not acceptable and extremely dangerous."
Police carried out raids against academics and seized computer equipment in other parts of the country. At least two universities have meanwhile launched internal probes into their employees who signed the document.
The senate of Kocaeli University issued a scathing condemnation of the academics, accusing them of supporting terrorism by "ignoring the blood of the martyrs," referring to security forces killed in ongoing fighting between government forces and Kurdish militants in the south-east.
The Turkish army says it has killed more than 370 alleged militants in just two districts in the south-east since it launched a fresh offensive last month.
One police officer and 19 alleged PKK members were killed Friday in Siirt, in the south-east, Dogan reported.
The PKK, listed as a terrorist group in the US and EU, has waged a 30-year battle with the state for greater rights and autonomy for the Kurdish minority in Turkey, which makes up at least 15 per cent of the country.
Kurds have complained of systemic discrimination for decades. The Kurdish language was banned for a number of years, though recently restrictions have been relaxed.