17 more charged over Istanbul airport attack
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.
Thirteen suspects had already been charged Sunday in connection with the worst of several attacks to hit Turkey's biggest city this year.
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.
Of more than 200 people injured in last week's attack, 47 people are still in hospital.
Authorities have identified the bombers as a Russian, an Uzbek and a Kyrgyz national.
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 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.