We strongly urge the Turkish government to stop prosecuting academics, to abide by international human-rights values and to respect civil liberties — including freedom of speech (see Nature http://doi.org/bbxj; 2016).

In a petition to the government this month, more than 2,000 academics from Turkey and thousands of international scholars have called for an end to the curfews and violence against people in Kurdish provinces. This prompted Turkey's President Recep Tayyip Erdoğan to order the Higher Education Board to take action against those academics he described as committing “treason”. Istanbul's Chief Public Prosecutor launched a criminal investigation based on Article 301 of the Turkish Penal Code, which prosecutes those who insult the state.

We are deeply concerned about this escalating crisis. We hope that the international academic community will join us in condemning these attacks against our colleagues in Turkey.