Three foreign nationals were detained at Istanbul's main international Ataturk airport over alleged links to the attack on a Berlin Christmas market in December, which left 12 people dead.
All three are German citizens of Lebanese origin, Turkey's state-run Anadolu news agency reported on Monday. They apparently had links to the attacker, Anis Amri. The detentions took place last week.
Last weekend, Anadolu reported that a German citizen of Jordanian descent was captured in Izmir, in western Turkey.
The Islamic State terrorist group claimed responsibility for the Berlin attack. Amri, who drove a truck into the crowded market, was shot dead several days after the attack by Italian police in Milan.