Turkish police on Friday detained 11 more people in relation to the investigation into the attack on Istanbul's Ataturk airport.
The arrests in Istanbul's Basaksehir district follow a series of raids and detentions a day earlier.
The Turkish presidency confirmed to NBC News that at least one of the suspects detained Thursday was a Russian citizen.
Turkish officials haven't publicly identified the attackers who killed more than 40 people at the airport on Tuesday. However, police sources told NBC News that the assailants were Russian, Uzbek and Kyrgyz.
Related: 'Second Front of Jihad' Looms on Russia's Border
While there has been no official claim of responsibility for the attack, officials have said it bears the hallmarks of ISIS.
Up to 2,000 Central Asians are believed to be fighting for ISIS in Syria and Iraq.
