German leftwing militants have claimed responsibility for an arson attack that damaged high-voltage cables in Berlin, cutting power to tens of thousands of homes and businesses.

The group, calling itself Vulkangruppe, said it targeted wealthy districts to protest climate change, fossil fuel use, and the energy demands of AI data centres.

Up to 45,000 households initially lost electricity and heat during freezing weather, affecting hospitals, care homes, transport, and mobile networks.

Berlin officials condemned the attack as extremist sabotage that endangered lives, while police launched a state security investigation, The Guardian has reported.

The outage echoes previous arson attacks linked to the same group, which German intelligence classifies as a leftwing extremist organization.