GRUENHEIDE, Germany, March 8 (Reuters) - Tesla's

German plant near Berlin will resume operations next

week, the head of its works council said on Friday, after a

power outage stopped production.

The Tesla electric vehicle (EV) factory has been closed

since March 5 after a fire at a nearby power pylon, which police

are investigating as an arson attack.

German police said they believed a letter from a far-left

organisation called the Volcano Group claiming responsibility

for the fire was authentic.

"We will restart the factory next week," Michaela Schmitz

told a gathering of several hundred workers at the electric

vehicle (EV) production site, known as a Gigafactory.

Some were holding a banner saying "We won't be shut down!"

"Alongside many chapters of outstanding achievements, this

attack will go down as a dark chapter in our history. But also

that will not stop us," said Schmitz.

The attack has left the site's 12,500 employees in limbo and

means the U.S. EV maker is unable to produce around 6,000

vehicles a week, resulting in losses that are expected to be at

least several hundred million euros.

Tesla's plant in Gruenheide has for years been the subject

of criticism by some locals and activists, who are concerned

about its environmental impact.

Schmitz said that Tesla employees would receive information

about the restart soon, but did not give any further detail on

the potential timing of it.

"Colleagues have been condemned to sit at home, instead of

contributing successfully together to the energy transition,"

Schmitz added.

Tesla has previously said that the factory might be without

electricity until the end of next week.

Germany's federal prosecutors office said on Friday it had

taken over the investigation into the arson attack, looking into

charges of terrorism and "anti-constitutional sabotage".