South-west Berlin back on the grid after worst outage since WWII

Power supply was restored to south-western Berlin on Wednesday after hundreds of thousands of residents were left without power in freezing temperatures following an attack on the grid that caused the longest outage in the German capital's post-war history.

Operator Stromnetz Berlin said all of the tens of thousands affected households would be gradually supplied with electricity again over the course of the next hours, after a provisional cable installation was successfully tested overnight.

Critical facilities such as hospitals and care homes were informed that power would soon be restored and consumers have been asked to disconnect emergency power generators in order to prevent damage.

Authorities also called on people to refrain from using high-power appliances like washing machines, dryers and kettles right after the power comes back on.

Some 45,000 households and over 2,200 businesses in Berlin's Nikolassee, Zehlendorf, Wannsee and Lichterfelde neighbourhoods were cut off early Saturday after high-voltage cables leading to a power station were set ablaze by what Berlin authorities believe was a group of left-wing militants.

Thousands of households have since been reconnected, and the city administration told dpa on Wednesday morning that operator Stromnetz Berlin aims to have everyone back on the grid later today, after previously setting a Thursday deadline.

Some 19,900 households and some 850 businesses were still without electricity for a fifth consecutive day on Wednesday morning, as temperatures remained below freezing.

In a letter of responsibility posted online on Sunday, the left-wing extremist Vulkangruppe (Volcano Group) says it "successfully sabotaged" a gas power station in Lichterfelde.

The group said its primary aim was to target the fossil fuel industry, noting that the action "resulted in power outages in the more affluent districts of Wannsee, Zehlendorf and Nikolassee."

"We apologize to the less affluent residents of south-west Berlin," it said.

Berlin authorities consider the letter to be authentic, with Mayor Kai Wegner describing the attack as an act of terrorism.

Germany's top law enforcement agency has since taken over the investigations, with prosecutors in Karlsruhe probing anti-constitutional sabotage, membership of a terrorist organization, arson and disruption of public services.