BERLIN (AP) — A series of fires hit railway infrastructure in the German city of Hamburg overnight, causing widespread disruption to trains between Hamburg and Berlin and between the port city and the Baltic Sea coast. Police said they suspect that the damage was politically motivated.

Railway operator Deutsche Bahn said that trains on the main high-speed route between Hamburg and Berlin were canceled because of vandalism. It said it was running some trains on an alternative route that takes up to an hour longer.

Long-distance trains between Hamburg and Rostock also were canceled. Deutsche Bahn said it likely would be able to restore service on the main Hamburg-Berlin line only on Saturday morning.

Hamburg police said that cable ducts next to railway lines were set on fire at three locations in the city between 2:30 and 4 a.m.

They said in a statement that they suspect “a political motive as the background” and are seeking witnesses, but gave no further details of the reasons for their suspicions. The fires were all extinguished.

A claim of responsibility that appeared on a left-wing website said that “transport arteries of the capitalist infrastructure” had been “sabotaged,” but referred to lines used for freight rather than passenger traffic, German news agency dpa reported. Police said they were aware of the claim and it was part of their investigation. It wasn't immediately clear whether the claim was authentic.