Up to 500 homes and businesses in central London's Westminster have been affected by a power failure.
UK Power Networks, responsible for electricity in the area, said the power outage was caused by an underground fault at around 0900 BST.
At 1130 BST, it said that all power had been returned to customers.
Millbank studios, where the BBC broadcasts some of its political coverage, lost power for about five minutes.
The energy supplier said Bridge Street and King Charles Street, in Westminster, had also been affected by the problem.
"We appreciate the difficulties of this situation and would like to apologise for the inconvenience caused," a UK Power Networks spokesman said.