Several people in Istanbul are being held over the double bombings that killed 17 people on July 27.
Besir Atalay, Turkey's interior minister, indicated that Kurdish separatist rebels were responsible for the explosions, and that most of those involved had been arrested. A prosecutor said separately that eight suspects should be charged with being members of the Kurdistan Workers' Party (PKK). The PKK denied responsibility for the attacks, but security services say the blasts displayed the hallmarks of the separatist group. The US and the EU also consider the PKK a terrorist organisation.
Prime Minister Recep Tayyip Erdogan earlier suggested the group was responsible for the bombings, saying they were a "cost" of the Turkish government's campaign against the separatists. However, PKK leader Zubeyir Aydar said his group was not associated with the attacks, implying "dark forces" may have carried out the bombings, an apparent reference to extreme nationalists.
The explosions happened about ten minutes apart on a busy street in Gungoren, with five children among the dead. They were the most serious attacks in Turkey since al Qaeda carried out a number of bombings in Istanbul in 2003. Around 40,000 people have been killed since the PKK initiated a campaign for self-rule in 1984.