Turkey's Higher Education Authority (Yok) has told pro-Kurdish students that they face expulsion if they press for Kurdish-language rights in universities.
The use of the language in universities remains a key demand of Kurdish rights groups. Students have frequently campaigned for more Kurdish rights, especially in the southeast of the country, which is predominantly Kurdish.
Until now, Yok has largely ignored such protests. Now students face sanctions such as suspension from classes or expulsion.
Yok has outlined activities that it considers unacceptable. They include emphasising the Kurdish identity, submitting petitions for instruction in Kurdish, reading Kurdish in class, replying in Kurdish to exam questions, organising plays in Kurdish and campaign placards and posters.
Turkey's human rights association accused Yok of undermining freedom of expression. Kurds are up about a third of the population, but restrictions on the use of their language have existed for decades.
One Istanbul University academic warned: "This takes us back to the bad old days when the generals ruled our country and freedom of expression did not exist."
Kemal Guruz, head of Yok, said: "These (demands) are planned and organised by the Kurdish Workers Party." The PKK has been fighting for a Kurdish state within Turkey in a conflict that has claimed more than 30,000 lives.