German police probe possible sabotage at two power substations

German police are investigating whether two separate incidents that disrupted electrical substations hundreds of kilometres apart were acts of sabotage, authorities said on Wednesday.

Damage to a power line was discovered on Tuesday morning at a substation near the Jänschwalde coal-fired power plant in Turnow-Preilack, around 100 kilometres south-east of Berlin. Electricity supplies were not affected.

Transmission system operator 50Hertz said devices found at the scene resembled "standard New Year's Eve fireworks," adding that further projectiles that had not been launched were also discovered.

Jan Redmann, interior minister of the eastern state of Brandenburg, said the act appeared to have been planned well in advance.

“We must currently assume that the perpetrators had been in the area for several days beforehand and had installed the relevant equipment," he said, adding that the construction and installation of the devices required a considerable amount of "technical know-how."

In western Germany on Tuesday evening, police were called to a substation in Bergheim, near Cologne because of a technical problem.

Several power lines failed following a short circuit, but there was no disruption to the general electricity supply.

Unknown perpetrators had placed cables across overhead power lines to cause a short circuit, North Rhine-Westphalia Interior Minister Herbert Reul said, describing the act as deliberate.

Investigators were working to identify those responsible, with a foreign state actor or left-wing extremists considered the most likely suspects, Reul said.

Reul said investigators were also looking into whether there was a possible connection to the incident in eastern Germany.

Police said they were coordinating closely with the substation operater, Amprion, and German grid operator RWE.

Five coal-fired power station units at two RWE-operated sites in Bergheim and Grevenbroich with a total capacity of around 4,200 megawatts were temporarily taken off the grid after the suspected attack.

The first unit has since been brought back online, with the further two expected to resume operations on Wednesday, an RWE spokesman said.

Germany's power infrastructure has been repeatedly targeted in recent months.

In January, suspected left-wing extremists set fire to high-voltage power lines near a power plant in south-western Berlin, leaving tens of thousands of households and businesses without electricity for days.