German police said on Tuesday they had found a flag of the Islamic State (IS) militant group near the site of a suspected attack on a railway track in Berlin and that investigators were examining whether the perpetrators had any political motives.
It is still unclear whether the flag and a text in Arabic found close to the railway track were left by the same people who damaged the overhead contact wire, police said.
"Since the beginning of the investigation, several pieces of evidence have been secured," police said, adding that authorities discovered a torn steel cable and the damaged overhead contact wire at the train track on Sunday.
Train operator Deutsche Bahn informed the federal police about the incident and local train services were temporarily interrupted, police said.
It remains unclear if there is any connection between the Berlin investigation and a similar case in Bavaria where unknown suspects tried to damage or even derail a high-speed train with a steel cable in October.