Tesla was not immediately available to comment on a report in the BZ newspaper that the fire had forced the electric vehicle maker’s Gruenheide factory to halt production.

Police said the fire brigade was working to put out the fire in a field in the area southeast of Germany’s capital Berlin, adding that the blaze had not spread to Tesla’s plant itself.

A police spokesman said they could not comment on the BZ report which said that the fire was started by environmental activists and that bomb disposal units were called in after emergency services found a sign saying “ordnance buried here”.

Tesla’s ambitions to expand its plant, which has a capacity of around 500,000 cars a year, hit a roadblock when residents voted down a motion to fell trees to enlarge it.

The US EV maker wants to double the site’s capacity to 100-gigawatt hours of battery production and one million cars per year, setting it up to dominate the European market.