A statement by Wandsworth Borough Police said: "Large police presence at Nine Elms, SW8 dealing with an incident at Battersea Power Station."
Wandsworth Road and Nine Elms have since been reopened after initial warnings from police for the public to stay clear of the area - however the police operation in the area is ongoing according to a Metropolitan Police spokeswoman.
Cringle Street, which leads up the the power station, remains closed.
The force was unable to provide any further information on the cause of the alert.
The iconic south London building is currently being renovated and turned into high-end flats, part of a regeneration project for the area following the construction of the US Embassy on Nine Elms Lane.
The coal-fire powered station had previously fallen into disuse after being decommissioned in 1975, however remained a key landmark on the London skyline with influences on architecture and art including the cover of Pink Floyd's 1977 album, Animals.