Train services in and out of London Waterloo are severely disrupted this afternoon, due to a fault on the tracks.
The disruption is impacting South Western Railway services, and is expected to continue until the end of the day.
"There is currently a fault affecting the electric power rail between New Malden and Clapham Junction. This means that there is no power being supplied to the line used by local stopping trains travelling in the London bound direction," National Rail said.
"Trains are able to run on the remaining lines, however, these may be disrupted as queues of trains build to divert onto these lines to bypass the affected area.
"Network Rail engineers are currently on site and are working hard to ascertain the problem and rectify it as soon as possible to get the line reopened."
The rail operator warned services may be subject to delays or short notice alterations, as some trains may have to divert their course to avoid congesting the area.