17 people, including 11 Russians, have been charged over the Istanbul airport attack, bringing the total number charged in connection with the suicide assault to 30. The latest suspects, who also include six Turks, were charged with "belonging to an armed terrorist group."
Ankara says the Islamic State group is behind the June 28 gun and bomb attack at Ataturk international airport, which left 45 people dead, including 19 foreigners.
13 suspects, including three foreign nationals, had already been charged Sunday over the worst of several attacks to hit Turkey's biggest city this year.
President Recep Tayyip Erdogan, speaking to journalists in Istanbul, said the suspects included men from Russia's volatile Caucasus region of Dagestan, as well as Kyrgyzstan and Tajikistan.
"The attack was launched as part of Daesh operations and bears the mark of its methods," Erdogan said, using another name for the IS group.
Police also detained two suspected IS jihadists - Kyrgyz nationals - at the airport on Sunday. Night-vision goggles and military clothing were reportedly found in their suitcases, along with passports in different names.
The men had just arrived in Istanbul from Ukraine, NTV television reported.
Prime Minister Binali Yildirim said Monday that security was being boosted at sensitive Istanbul sites such as metro stations, with 80 special forces troops patrolling Ataturk airport.
Authorities have identified the bombers as a Russian, an Uzbek and a Kyrgyz national.
Read more: Istanbul airport attackers hail from Russia, Uzbekistan, Kyrgyzstan, - Reuters
State news agency Anadolu named two of them as Rakim Bulgarov and Vadim Osmanov, without giving their nationalities.
Central Asia's former Soviet republics have been a major source of foreign jihadists travelling to fight with IS and other extremist groups in Iraq and Syria.
Turkish media have identified the strike's organiser as Akhmed Chatayev, the one-armed Chechen leader of an IS cell in Istanbul who allegedly masterminded two other deadly attacks that killed tourists in the city.
Turkey has been rocked by a series of attacks over the past year, blamed on both IS jihadists and Kurdish rebels.