The raids came after bomb blasts in two cities in southeast Turkey killed nine civilians and wounded dozens
Turkish police detained 17 people as part of an operation aimed at Kurdish militants early on Thursday, conducting raids across Istanbul, including at the offices of the pro-Kurdish Peoples' Democratic Party (HDP), state-run Anadolu Agency said.
Backed by a helicopter, counter-terror squads raided HDP offices in the central Istanbul district of Beyoglu at 3 a.m. (0000 GMT) as armoured vehicles and a water cannon vehicle were deployed nearby, the Dogan news agency reported.
The raids came after bomb blasts in two cities in southeast Turkey killed nine civilians and wounded dozens on Wednesday evening, according to security sources who said Kurdistan Workers Party (PKK) militants were responsible.
A top PKK commander had warned at the weekend of fresh attacks, saying police "will not be able to live as comfortably as they did in the past in cities."
The HDP, parliament's third biggest party, wrote on its Istanbul Twitter account that police had broken open the door of its building and "illegally" searched the offices when no party official was present.
The raids, in 10 districts across Turkey's largest city, targeted the "urban structure" of the PKK, Anadolu said.
It said the detainees were accused of "terror group membership", recruitment and staging illegal protests.
The PKK, designated as a terrorist organisation by Turkey, the European Union and the United States, took up arms against the Turkish state in 1984 and over 40,000 people, mainly Kurds, have died in the violence.