Production at Tesla’s electric vehicle plant near Berlin came to a standstill and workers were evacuated after a power outage that officials suspect was caused by arson.

According to the Interior Ministry in the state of Brandenburg where the plant is located, unknown perpetrators are suspected of deliberately setting fire to a high-voltage transmission line.

The early morning fire on Tuesday caused the power supply to fail to the surrounding towns, including Grunheide, where the Tesla factory is located.

Brandenburg’s Interior Minister Michael Stubgen said initial findings indicate the fire was intentional.

“If the initial findings are confirmed, it will be a perfidious attack on our electricity infrastructure,” Mr Stubgen said.

Police said they have been made aware of an emailed “letter of confession” which they were examining, German news agency dpa reported.

It said a far-left group called Volcano Group accused Tesla in the email of “extreme exploitation conditions” and called for the “complete destruction of the gigafactory”.

It was not clear who the email was sent to or who was behind the group.

Elon Musk, who is Tesla’s CEO, condemned the incident.

Referring to the possible attackers Mr Musk, who owns about 13% of the Tesla stock, wrote on X, formerly Twitter, that “these are either the dumbest eco-terrorists on Earth or they’re puppets of those who don’t have good environmental goals”.

“Stopping production of electric vehicles, rather than fossil fuel vehicles, ist extrem dumm,” he added, using the German words for “extremely stupid”.

Brandenburg governor Dietmar Woidke also condemned the alleged attack.

He said: “This is obviously a serious attack on our critical infrastructure with consequences for thousands of people and many small and large companies in our state.

“Attacks on our critical infrastructure are a form of terrorism.”

The power outage at the Tesla factory comes as environmental activists have been staging a protest in a forest near the plant against plans by Tesla to expand.

The “Stop Tesla” protest has seen dozens of activists put up tents and built treehouses, some of them several metres above the ground — a tactic used in previous German environmental protests.

Tesla opened the factory in Grunheide in March 2022, launching a challenge to German automakers on their home turf.

The company now wants to expand the facility to add a freight depot, warehouses and a company kindergarten.

Those plans would entail felling more than 100 hectares (247 acres) of forest.

It has drawn opposition from environmentalists and some other local groups, who also worry about possible effects on the area’s water supply.

In a nonbinding vote in mid-February, residents of the municipality rejected Tesla’s plans, which still need approval by local authorities.

About 12,500 people work at the plant.