In the early hours of Tuesday, several fires broke out at the site in the eastern Marzahn district, affecting cranes and train signalling cables, Berlin police said in a statement.

“Investigators believe it was arson, and a political motive is being examined,” police said Tuesday, adding that car traffic and trains in the area were affected during the operation to extinguish the blaze.

The police did not give further details about the potential motive, but a far-left group posted an anonymous letter on a website saying they were responsible, according to local media reports.

They said construction firm Strabag, which operates the site, was involved in the controversial expansion of a factory run by Elon Musk’s electric carmaker Tesla in the town of Gruenheide outside Berlin.

They said the company was building a freight yard at the Tesla plant, to be run by state rail operator Deutsche Bahn, and that swathes of forest were to be felled for the project.

Musk has also attracted growing criticism in Germany since he backed the far-right AfD party ahead of last weekend’s national elections.

Tesla opened the plant, its only production location in Europe, in 2022.

At the end of 2023 it announced expansion plans, aiming to double capacity to one million cars a year at the site, which employs some 12,000 people.

The US company scaled back its ambitions after local residents opposed them in a vote.

But the plan has nevertheless continued to generate anger among local residents and environmentalists.

In March last year, the plant was forced to halt production following a suspected arson attack on nearby power lines claimed by a far-left group.

Activists also built makeshift treehouses in the woodland around the factory to protest the expansion and environmentalists have demonstrated at the site to protest the enlargement plans.