FRANKURT, Germany–Tesla halted production at its German factory Tuesday after assailants allegedly set fire to high-voltage lines nearby, cutting power to the US electric carmaker's only plant in Europe, the company and authorities said.

Emergency services were called to reports of a burning electricity pylon southeast of Berlin in the early hours, in the area the factory is located, and firefighters extinguished the blaze.

But it knocked out power to the Tesla factory, as well as surrounding villages, and police have launched an investigation into suspected arson.

Environmental activists opposed to a planned expansion of the Tesla factory recently set up a camp near the plant, but police refused to be drawn on whether there was a link between the group and the blaze.

Michael Stuebgen, interior minister for Brandenburg state, said that "if initial findings are confirmed, this is a perfidious attack on our electricity infrastructure".

"Thousands of people have been cut off from their basic supply and put in danger. The rule of law will react to such an act of sabotage with the utmost severity."

But he cautioned against "premature speculation" about who might be responsible.

Tesla said in a statement that the production facilities were in a "safe state" after the shutdown, and workers had been sent home.

"We are currently unable to say when production can be expected to resume," it added.