A nationwide manhunt for a 22-year-old Syrian man suspected of planning a bomb attack was under way in Germany on Sunday, as three of his alleged accomplices faced criminal charges in court.
The manhunt was triggered by the discovery of explosives in a flat in the eastern city of Chemnitz.
Police said it remained unclear whether main suspect Jaber al-Bakr had links to the Islamic State terrorist group or whether he was armed, warning the public to be careful.
They have also refused to comment on a report by Focus magazine that a German airport was the intended target of an attack. Security was beefed up at both Tegel and Schoenefeld airports in Berlin late Saturday.
Three other Syrian men believed to be accomplices of Jaber al-Bakr were due to appear in court later Sunday.
They are being investigated on suspicion of preparing an act that would endanger national security, according to a spokesman for investigators in the city of Dresden.
They were arrested Saturday in Chemnitz where a high-rise residential block had been put on lockdown as police raided the flat.
Several hundred grams of explosives were found there, which police later destroyed in a controlled explosion.
It was unclear whether al-Bakr had arrived in Germany as a refugee. Some 890,000 migrants arrived in the country in 2015, many of whom had fled the ongoing conflict in Syria.
Germany has been on high alert since two terrorist attacks occurred over the course of one week in July. Both were claimed by Islamic State militants and carried out by asylum seekers.
At least five Islamist attacks have been thwarted by German police since 2007.