German police are searching for a 22-year-old Syrian man who fled after they found traces of explosives in a flat in the eastern German city of Chemnitz on Saturday.
Police said they had launched a manhunt for Jaber al-Bakr across the eastern state of Saxony. Security sources told dpa there was a suspected connection to the Islamic State extremist group.
"We want to find him as soon as possible," regional police spokesman Tom Bernhardt said.
Local police were informed about a "serious threat" by German intelligence on Friday night, Bernhardt said.
Suspicions of a planned bomb attack led special forces to put a high-rise apartment block on lockdown for several hours on Saturday.
Special forces stormed the apartment around 1 pm (1100 GMT) to find the rooms empty.
It was initially unclear if al-Bakr 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.