File picture: Reuters

Berlin - Closed schools, shuttered businesses, cold apartments, dead phone lines: More than 30 000 households in the German capital were without power on Wednesday after a mishap at a construction site led to a blackout that lasted more than 24 hours.

The outage hit after a construction worker at a bridge renovation project accidentally severed a main power line and the replacement cable on Tuesday afternoon, cutting off energy to the city's south-eastern Koepenick district.

Power is unlikely to be fully restored until about 9:30 pm (2030 GMT) on Wednesday, said Julia Klausch, a spokeswoman for energy company Vattenfall. The power cables that were damaged during construction work on the bridge must be entirely replaced, she said.

Around 2,000 businesses were also hit by the power outage. Schools and day care centres in the affected area remained closed while workers laboured to fix the situation.

A partial restoration of power to about half of the affected households and businesses was expected in the early evening. There were several elements to the repair process that workers had never previously confronted, the spokeswoman said.

Many of the affected buildings rely on electricity for heat, meaning residents were forced to endure a cold night, despite relatively mild temperatures for February.

Vattenfall said heat could only be restored to the 5,000 affected residences once the power is back on.

Emergency crews had set up an additional power supply to help a hospital in the affected area get through the night, while some patients in need of extra care were transferred to other facilities.

Police have been out on affected streets in extra numbers to help ensure order. Many traffic lights were not working, and tram lines were unable to run without power.

Adding to the problems, neither landline or mobile phones were working in the region.