Following the arson attack on the electricity supply to the electric car company Tesla's factory near Berlin, the German Federal Public Prosecutor's Office has taken over the investigation, a spokeswoman said on Friday.
The country's top prosecutor is taking charge of the investigation due to an initial suspicion of membership of a terrorist organization, anti-constitutional sabotage and arson committed by more than one person, she said.
"No further information will be provided at this time," she added.
As yet unknown perpetrators set fire to an electricity pylon in a field on Tuesday which also supplies the Tesla factory. Production was stopped. Tens of thousands of local residents were also affected by the power cut.
The left-wing extremist Volcano Group declared that it was responsible for the attack. The police believe that the letter of confession is genuine. They are looking for witnesses who noticed the night-time attack or who can provide information on suspects.
The regional public prosecutor's office had previously investigated the offence - for anti-constitutional sabotage, disruption of public businesses and arson.
Tesla and an Edeka logistics centre have so far not been able to be supplied with electricity again since the arson attack. The grid operator EDIS spoke of massive damage to the pylon and live infrastructure.
According to Tesla, production at plant in Grünheide just outside Berlin is expected to remain interrupted until the end of next week - longer than initially thought.
On Thursday, German Interior Minister Nancy Faeser called for a crackdown on left-wing extremists.
"It appears to have been a suspected left-wing extremist action; it was a serious arson attack that has left many, many thousands, especially households, without electricity," the minister told dpa on Thursday.
She condemned the fact that the attack led to power cuts in hospitals and doctors' surgeries, which could be life-threatening.
Faeser said in the video interview that "left-wing radicalism is becoming tougher, more violent and does not shy away from such actions, and we must have a tough response."
She said prosecutors should crack down "and severe penalties must also be imposed."
