Turkish news reports say police are carrying out raids and detaining people suspected of involvement in violence against police during a wave of anti-government protests.
NTV television says the raids in Ankara and Istanbul are targeting left-wing groups.
Turkey's state-run Anadolu Agency said at least 25 people were detained in Ankara and many others in Istanbul.
Earlier, police detained a dozen people who stood still at Istanbul's Taksim Square in a form of passive defiance against Prime Minister Recep Tayyip Erdogan's authority after activists were ousted from a sit-in at a park over the weekend.
The wave of anti-government protest that has swept through Turkey starting May 31 has shaken the country's secular democracy.
