Turkish state-run media say police have detained nine people in connection to a double bomb attack that killed 17 people and wounded 150 others in Istanbul Sunday.
The Anatolia news agency Wednesday said the nine are suspected of having links to the bombers. The agency did not provide details of the suspects' identities or background.
No one has claimed responsibility for the bombings. Several groups have carried out bomb attacks in Istanbul in the past, including Kurdish separatists, far-left activists and Islamists.
Istanbul Governor Muammer Guler has said the bombings appear to be linked to Kurdish rebels of the outlawed Kurdistan Workers Party, or PKK. The group has denied involvement.
The PKK has been fighting for self-rule in southeastern Turkey since 1984. The violence has killed more than 30,000 people.
Turkey has stepped up military operations this year against PKK rebels both in Turkey and in northern Iraq, where thousands of rebels are based.
Turkey's military says its fighter jets bombed PKK targets in northern Iraq Tuesday, killing an unspecified number of militants in a mountainous Qandil region, along the Iraq-Iran border.
The military says its forces also bombed a second rebel target, in the Zap region, near the Turkish border, but military officials did not offer further details on that strike.
Some information for this report was provided by AFP and AP.